Its a hard one to crack, too badly decomposed to say, can't see any breast tissue left, or any sexual organs, and can't see the size of the hips either.
You can tell with the bone structure of the skull. A male has a heavier brow and squarer jaw line usually, etc. I think this might be a male but it's hard because I can't see his brow and forehead. The nose looks prominent and the chin looks square that's why I think it's male.
Its a male, his shoulder bone is extending out past his hips, the male shoulders always extend out past the hips as a female her hips extend out past her shoulders, its a great way to tell if a man is really a woman or vise versa.