I do not understand this thread.
let me get this straight. (Interesting choose of word there)
You know a guy, he is sort of your friend, his perfect, you want to make a move, but your unsure whether or not he is gay.
I got two pieces of advice -
Instead asking him whether he is gay or not, ask him out on a date like you would if you did not doubt his heterosexuality. Now, obviously if he declines, that by no means actually constitutes him as gay, but whether he is gay or not would not matter because he does not want to be with you.
Also, never take the advice on ones sexuality from others. Especially if it is in the context of primary, secondary, college or even university. People have a habit of lying to degrade another individual.