If he is really gaited, then it depends on what type of gait he does. Just going off his appearance, he could be a full QH, a breeding stock paint, a cross of pretty much anything with one of the gaited breeds like STB, Walker, MFT, etc.
In other words, your guess is as good as mine.
Is it just the picture or is there really that much weirdness going on with his throatlatch area?
...or is what I'm seeing just some really oddly placed and poorly done photoshop job?
...or, looking again, it may just be the person's hand under his jaw...maybe.