Hi, No, they aren’t interchangeable. Only “He turned out to be married” is correct. The other one is grammatically incorrect.

I corrected them. It turned out he's married. He turned out to be married.

As Profe José demonstrates 'it turned out . .' and 'he turned out . .' are used in different contexts. They are both statements of what later became evident; however 'He turned out . . ' refers to the character or activity of a particular person, while 'It turned out . . ' does not necessarily do this, and could refer to a situation in general.

He turned out to be a very nice guy. He turned out to be a very mean fellow.

It turned out he's married. It turned out he was married.