Well, of course I see German Shepherd, too. I think that there's definitely some GSD in there based on his ears and coat. Both color and texture. (As much as you can tell texture from a photo..hahaha!)
But, his mask and schnozz do look kinda bigger, like perhaps a mastiff. But, I've also seen some kind of jowly labs, and there could even be some bloodhound there.
Mixes are just too mysterious. Something that seems for SURE a trait of one dog, could really be a trait of another breed that looks a particular way in relation to the traits of all the others! hahaha! He's adorable, and if I absolutely HAD to say, I would say Akita and GSD for sure, and probably either some bloodhound or maybe bullmastiff.