A male will have a pronounced bulge at the base of his tail. You will know it when you see it it isn't difficult to see. I don't see that here and would have to say it is either a female or too young to have a bulge. The bulge didn't become really distinct on mine until he was about 9 months old.
Maybe someone with more experience can weigh in if I'm missing something.
Edit: As I look again I realize I just can't tell at that angle. There might be a bulge, or there might be a trick of the light not really sure. Can you get a more direct shot of the tail base?