Italian is not an international language like English or Spanish for instance, but still it’s the language of many cultural activities which are renowned worldwide, such as opera and figurative arts. Apart from that it strikes me that students don’t come to a site like this for doubts they may have about grammar, etc. (as a student I’d have used a site like this). So why do we attract so few users? Should the site be somehow more visible to new potential users? Could anything be done in that respect?
This is a problem I have grappled with in the past, and I have to say I am somewhat depressed by the current state of affairs. In this answer I will just randomly post my thoughts on the matter (so this is just my personal opinion and no kind of official statement as a moderator)
Who is the audience for this site? I think I can distinguish pretty much three groups:
People that are not native speaker of Italian, but that want to learn Italian. These people are few. It hurts to say it, as a person who deeply loves my language, but Italian just does not have the cultural cachet other languages have: it's spoken at best in one country and a third of another (if we want to consider Italian Switzerland as a third of the country, which it isn't by population) and there is precious little culture of international relevance that is produced in Italian. We have, this is true, an immense artistic patrimony, starting from the twelfth century, which has been incredibly influential in the past centuries, but apparently it is little read outside of Italy. Certainly not enough to substantially push people to learn the language. Just for comparison look at literature.SE: they have 58 questions on French literature, 45 on German literature, 35 on Spanish literature, 81 on Russian literature but only 14 on Italian literature. I'll refrain to comment on the state of current Italian "pop cultural" production, let's just say I don't think that as a whole it's very attractive for foreigners. Regardless, we do have some users in this group (and I cannot fail to mention Charo :)), but the truth is that this group is a lot shallower than we'd like.
People who are interested in the history, evolution or special features of the Italian language. I consider myself part of this group (and I suspect, a large part of the regulars of the site are too). These people are also few. To begin with, they are mostly native Italian speakers, who are not exactly a huge percentage of world population (even of Western world population). Moreover, this kind of scholarly pursue is not very attractive to the majority of people. Despite that, we are doing fairly well with this limited pool. This is the kind of users that keep the site afloat.
Italian speakers that have grammatical doubts. Who are these people? There are a few adults (but not that many: most "professionists of the word" that are required to write professionally are more than able to open a grammar, and tend anyway to fall in the second group too), but mostly as I see this would be composed by students. I doubt grammar is taught in school after middle school. I certainly did the grand total of one hour of grammar in high school (on the correct usage of capital letters). This was more than twelve years ago, but I doubt the situation has improved (if anything, the rumors I hear suggest the emphasis on grammar has decreased). Even ignoring that it is against the ToS for an EU citizen of less than 16 years to have a SE account (the policy here is rather of the "don't ask, don't tell" variety), my recollection of grammar as was taught in middle school consisted in a long litany of complements to memorize, not the actually interesting kind of grammar (e.g.: how do you choose tenses in indirect speech, when do you use the subjunctive in the subordinates, etc.). Moreover, my impression is that few teenagers use the internet for anything but Facebook or Instagram these days, or possibly doing "let's play" on Youtube (but it might well be flawed). Of course someone could argue that you can have grammatical doubts when writing essays, even if you do not study grammar formally in school. This is certainly true, but I don't recall that being a common occurrence when I was in high school. In the few cases I remember, the solution was raising your hand and ask the professor for the correct form (remember: in Italian schools most essays are written in a classroom setting, without access to the internet!)
So on the whole the audience for this site is small. This is the core problem that we are grappling against.
What to do then? I'll confess I don't know. I toyed for a bit with the idea of doing a poem of the week, to be posted somewhere related to this site (probably the Bar Sport or some kind of meta post), maybe in collaboration with Literature.SE, to raise the profile of Italian literature. I doubt it would have a lot of effect, though, and I found hard to find the motivation to do so. Another idea I had was to organize small competitions of the kind they have in different stacks (e.g. I'll gift 200 points to the best question on the topic XXX this week). But I doubt we have the sufficient critical mass of users to really make it work.
So, this is it. I don't know where do we go from here. Sorry if I close on a somewhat depressing note.
I would also like to see how this site increases its activity: I love to read interesting questions and answers from different people.
I sometimes fear we have fallen into some kind of vicious circle in relation to voting. Voting is essential to keep users contributing to the site with both questions and answers. Since we have few users really active, we have few votes (have a look here and here) and, since we have few votes, this doesn't help to attract new regular contributors (on the contrary, my impression is that lately we have lost some contributors). We have already discussed this problem here, but I would like to encourage users of this site trying to vote more often.
Despite the small amount of votes, I believe we are producing good contents. For sure it's contents considered of interest since we are having more than 3000 visits per day. If you have a look here you will see that the Notable Question badge has been awarded at present 223 times, which means that there are 223 questions that have received more than 2500 visits. I would like to encourage users who have made that possible to keep doing so.
To say something more positive, since Gio has mentioned Spanish in his question, I've realized over years of learning Italian as an autodidact that Italian has a great amount of excellent online reference works and resources, as you can see here, some of them better than the ones you can find for Spanish. For instance, there are lots of excellent online Italian dictionaries and I can assure you that they are impressively better than Spanish ones. I believe that this has also something to do with the small amount of questions on this site.
In addition to all this, I've just found this Meta anwser that shows how our site is growing: comparing 2018 to 2017, ordering Stack Exchange sites created before 2017 by percentage change of posts, Italian.SE is at position 14 and it has been an increase of 26.05% of questions and of 11.92% of anwsers with respect to 2017. So, I would like to encourage all users of this site to keep allowing such a growing.