Well, the only thing that is impressive is how many that is getting fooled by this. He use layers and a special brush so it looks like he painting. What happens is that he´s revealing the photo gradually while adding some smear/fuzz/slight texture.

This is fairly common on Artstation, the problem here is that the…

Well, it´s a little technique called “Painting over photos”. Here´s a little video to show the workflow of such digital process: