Wait a minute. Doesn't speaker = writer = Shakespeare? Not so fast. Although it's reallllly tempting to map him on to his poetry, there's no autobiographical evidence that the "I" of the sonnets = the i in "Will." What we do know is that the speaker is male and up to his eyeballs in love with a younger man, the same "fair youth" that the first 126 sonnets are written to.
So does that make the speaker gay? The debate continues. Some scholars have argued, "Yes, of course, because he's a man in love with another man." Others are less sure, claiming that these sonnets are less about romantic or sexual attachment and more about general admiration. It's true that in Elizabethan England the beauty of young men was more openly celebrated than it is today, by both men and women. On the other hand, 126 sonnets is a lot of love poetry to write to a guy you aren't really into.
So is it gay, or can't really say? Take your pick.