There's a guy in my school that I really like he's super nice and cute and stuff but I have no idea if he's gay or streight and I'm shy as all hell so I can't just tell him how I feel without knowing if he's gay or not
You should honestly get closer with him first. Feel him out on LGBT issues or just how he feels on the subject. If you guys get close enough he may open up to you or it may be easier for you to open up to him. You don't have to outright ask him his opinion right away. Just make a friend first and go from there.
Get to know him first. Become friends and as Nico said, check out his opinion on LGBT+ topics. If ypu get close enough, you could come out to him. And then proceed. Don't just ask him outright. He could think of it as rude. Befriend him first.
Are you friends with him? Like, are you on talking terms? Like others have said, get to know him better, then to can try to find out.