If alien extraterrestrials exist, are some of them gay?

Well if they exist or not is not really the point. If they exist they are so far away that contact is impossible. Many people, apparently half of America, claim they believe in ET and don't appear to be at all materially troubled by some minor inconvenience such as total lack of evidence. 

To compensate for the absence of evidence, adherents create extraterrestials in their own mind, in  their own image. If the adherent is gay, it is fair to suppose that their delusions feature gay extraterrestials. However since all depictions of ET that I have ever seen have a striking lack of any variety of genitalia, then one can only suppose that the delusional gay believers in ET endure a state of perpetual frustration. Maybe that is why believers always seem to be angry.