Yes, but people also call V a "he" and that doesn't mean anything.
Of course, I think that Xykon's pretty obviously male. But then again, I thought the same of V (really surprised when I found out people thought otherwise).
But this is crack pairing, not entirely reasonable and justified by canon pairing! The living picture of Xykon looks ambiguous enough and with a few modifications, voila!
YOU WILL NEVER SEE THIS NOW! (See below)
SHE LIVES!