Have a crush on this guy who works at a restaurant. I don't know how to approach him.

So I have known of this guy for about 9 months now. His name is Curtis. He works as a host at a breakfast restaurant right next to my university. From the first time I saw him I thought he was pretty cute. Ever since I have been going to the same place almost every weekend trying to work up the courage to ask him out. The main problem is, of course, that I don't know whether he is gay or not. He seems gay to me, but I don't want to make generalizations, and honestly I'm not sure if I'm just being hopeful.I don't really know the guy, but I want to get to know him. I don't want to straight up ask him out, because I don't want to put him in an awkward position while he's working, and I also don't want to get rejected lolI was thinking about asking him to hang out, and be like "Oh hey, you seem like a pretty cool guy, would you want to grab a drink sometime?" Would that be too weird?It has gotten to the point where this crush has affected other potential relationships I might have. Every single time I start dating some other guy, the first thing that comes to my mind is that I won't be able to keep pursuing Curtis, and then every time I am not seeing anyone I go right back to trying to approach him.Anyway, does anyone have any advice? I could really use some help.