Yeah, the Winter Soldier's specific circumstances are extreme for what a normal therapist might encounter, but yes, he was still a long-term POW, and a war vet, I would be incredibly surprised if he doesn't have PTSD.
Part of me wishes I had the training to try to put him through therapy and make it sound realistic, but I lack that training and I am not brave enough to try to fake it. Besides, I suspect that Bucky would flat-out refuse it.