Can't really tell from the picture, but I'm guessing female. Male's concave plastron is very exaggerated. And I'm not seeing that in the picture. Can I see the tail. Just turn the tortoise so the head is at the top of the picture that way we can see the gular and the tail in the same picture.
The two on the left are male and the one on the right is female. Do you see what I mean when I say the male's concave plastron is very exaggerated? the male in the middle might be a little younger because his plastron isn't quite as concave as the one on the left. But the female is so obvious when you have the two males to compare to. Also, the middle male's gular has been chewed off, so you can't use that feature to help with the i.d.