It can be either, but in general people are more likely to say "is" than "was". If you use "was" you're emphasizing that he is no longer alive. Otherwise, you can say "is", which doesn't have any particular emphasis and therefore is more widely used. You can say "is" because this is a photo of Michael, and it still exists, and he still exists as a photograph. You can say "was" because this photograph is am image of Michael, and Michael unfortunately no longer exists.

Both can se used, because “is” means that you’re talking about the picture you’re showing , and “was” is more about the person (in past). :)

Edited, because I misread your question. Both answers are possible, but I think "is" sounds the most natural, because "this" seems to be referring to the photo. You're really saying that this is a picture of Michael Jackson, not that this is the man himself.