Twitter is your friend here. DM everyone you can, and keep checking in with them to see if they're getting value out of it.
My personal experience was that I showed up, was delighted to see so many relevant papers, but then lost interest due to zero discussion.
That doesn't mean that it's not interesting. It is. But when you're making a social network, you're fighting a massive amount of inertia. The default case is for no one to come.
Give us a reason to keep coming back, and we will.
FWIW I speak from experience, having spent a few years running an HN clone that eventually tapered off.
EDIT: Also, your upvote algorithm needs a bit of work. The most upvoted papers are currently hidden on the second page. And in fact, at this stage, pagination doesn't make a lot of sense -- just show all the submissions.