The image isn't a fake in the sense of the usual 'stuck a wolf in there with photoshop' kind of fakery. In that respect it is a true record of events captured on film. The allegations involve whether or not the image was staged, ie. a tame wolf in captivity. From the evidence I've seen so far, it is not looking good for the photographer. Whichever way you look at it though, it is still a striking image. Admittedly, I find it less striking when I consider it as a doggy jumping a fence in a cage, rather than a wolf hunting in the wild.
If it is indeed staged, the photographer is a numpty for not declaring it. He's still a good photographer though….