Arh hah, let me tell you the new generation expressions!
『同性恋者』is too formal to address a gay man. I would say it's equivalent to "homosexual".
The popular terms to the concept in Chinese have nothing to do with their original meanings, just as "gay" now has nothing to do with "joyous", but instead, they directly take after English counterparts.
Comment: Now in Chinese net community, the word 直男 is stigmatized by extreme feminists, referring to conservative, male-chauvinistic men. So it's now not a strict equivalence to "straight" in gender preference aspect.
He looks like a gay.
Comment: Don't suspect! It is actually a transliteration of "gay", and it IS the most common expression. And for this reason, often it's used unchanged as "gay".
Comment: To avoid being seemingly harsh, often we use some tricks to soften the tone to show our innocence and acceptance. As in example, 辣 is a homophonic substitute to 啦, and a cursive ~ conveys (somehow) cute tone.
Comment: WARNING! Many homosexual people may feel offended by addressing them 『基佬』. It's derogatory. The etymology of 『基』meaning homosexual related is now hard to determine. Here are two explanations: 1. 基 in Cantonese is pronounced very similar to "gay". 2. In ancient Chinese, 㚻 （ji1）is the character for homosexual practice, which has evolved to 鸡, finally to 基. But whatsoever, 基佬 in Cantonese （as in Mandarin now）is derogatory. However, 基 used alone is not derogatory, as in 『腐眼看人基』.
Nah~ I used all four ways to express "gay". May this short paragraph help your own writing!