Well, it involved a lot of trial-and-error but I'll give you some ideas to try out.
Firstly, I set 2 duplicates over-top of the original then started with a 2nd duplicate in ACR. I made adjustments with the basic sliders, in particular Dehaze and then the colour adjustments in HSL. With this one and back in CC, I applied these adjustments to the 1st duplicate to the improved areas with masks. From here, I used numerous curves adjustments (again on duplicates) targeting the hazed areas of his face and hair and applied these to the layer below with masks. As for the right side of his mouth and his right eye, I selected his left eye and left side of his mouth, copied them to new layers, inverted the copies and used masks to apply them to the duplicate below.
I chose to make all of his sweater the same colour so I made numerous selections within his left side, copied them to new layers and moved them over to hazed side. Lots of transforming and the use of masks got them to what you see.
More curves adjustments helped with the shadowed areas of his hair, contrast improvements, etc.
I hope this is of some use to you. This one was surely not 'a one button fix'. :^)