I find that for every 100-200 readers, there's about 1 commenter. And even then, there are only a few dedicated commenters on the site who make an effort to discuss, joke, chat, etc. (I can list off a quick list; Hobbes, Amet, TristanJensen, hyena, etcetc.)
I've got 2k on Time Gate but only around 10-12 regular commenters who, well, always comment lol everyone else is either a suscribe-and-runner (which happens yes; if you check your stats page and look at your daily viewcounts, or at least the view counts each time you update, you'll see that on average, maybe only 50-75 people actually regularly check back to read your comic more and don't just subscribe and take off, which is another thing you have to take into account).
I'd say promote discussion where you can, but don't force it. Some people just don't comment, and prefer the typical lurking; others might just not have anything to say about your comic yet, especially if it's still just starting out and not much has been established. Maybe post a question in the comments section every few new episodes or so (don't overdue it is what I'm saying) to promote some discussion. But don't force it. I know this sounds like I'm shooting you down, but you only have about 100 subs so far, and as pointed out above, probably only 50-75 of those subs are dedicated readers, possibly less, possibly more, and those readers might just not like commenting, or it might just not be the right "time" to comment because they simply have nothing to say. And TBH, if there's simply nothing to say, then I'd rather have 5 well-thought out and good comments on an episode than 100 spammy ones.
So yeah, give it time. Those comments will come in soon!