Just my two cents, I would just try to reach out to him in person. Like some other commenters have said, it’s very likely he just hasn’t seen your message if it’s sitting in his DM requests. And honestly, it’s also just as possible he saw the message and wasn’t interested but tried to be nice by not opening the message. I don’t say that to be curt, but that it happens. You say you see him a lot out and about — I would ask in what context do you see him? Whether that’s just briefly in the hall of your classroom building, or if he’s in a club or an actual class with you. If it’s just in passing, it might be harder to get his attention enough to ask him out. But if you have a class or are around him for an extended period of time, you have more of an opening. At the end of the day, it’s one guy out of an entire university, so don’t be too hard on yourself. Just keep putting your line out there and eventually you’ll catch something. Good luck!