Is Yoshi gay

Sorry? Yoshi is obviously not a homosexual. >.<

Depends on quite a lot of things : first, is Yoshi male or female? He officially is a male, and widely accepted as male, but some people believe Yoshi's a female because he lays eggs. Then, is he or not in an actual relationship with Birdo? And finally, is Birdo a male or a female? In Japan, Birdo is widely considered as a male (The Japanese website for Double Dash says that Birdo "seems to be Yoshi's girlfriend, but is actually HIS BOYFRIEND") but it's a bit ambiguous in America. And well, last thing you might want to consider is if Yoshi KNOWS Birdo is a guy or not. :p
(Also, he might be bisexual or pansexual, but that's pushing the analysis a bit too far, isn't it?)