I think it's such a highly individual situation. So many factors come into play, like how long he was under his father's influence, did he have other positive influences in his life, etc. It's my unprofessional opinion that the less time you've lived with a toxic parent, the better your chances of not being scarred by them. Then again, lots of people are able to overcome abusive situations and lead relatively normal lives.

Just be cautious and take the time to get to know him in person. Has he had other long-term relationships? Does he drink excessively or use drugs? Those are a few things I would pay attention to.