Is it based on sex organs or gender?
If it's by the former? Then yeah, it is kinda gay.
If it's the latter (gender being a social thing, which is mostly, but not always shaped by biological sex), then it's more debatable.
If somone is attracted to a man, who has a cunt, and they are also male? They're gay, as it's male attracted to male.
Male attracted to a male with a dick? Gay.
Male attracted to a female with a cunt? Straight.
Male attracted to a female with a dick? Straight.
It depends on the gender, really. Like the whole 'yeah but the futa/dickgirl solo art is then showing off dicks!' doesn't hold that much water, since it implies the viewer would enjoy it just as much if it was a fully male bodied and gendered character doing it.