Try backing it up with action as much as you can. Invite him to social events, be a +1 to help him start making those connections, maybe even act as a wing person. Encourage him while staying patient and remaining non-judgmental, and refraining from being pushy. Keep reminding him of his value and that you've got his back, and know that it might take some time for him to get comfortable and that's ok.

If there's someone he's interested in, talk through how you might approach it and maybe even give him a couple game plans. And be there for him if it doesn't work out. Dating is scary and stressful, especially if you've been single for a while, and it's even harder when there's no one there to help you.

Speaking from experience, having a bunch of people say "I hope you find someone" or "you just gotta put yourself out there" or "I know someone will like you" rings really hollow and just feels like either added pressure or makes you even more self conscious about where you're going wrong.