It depends on how you want to define "tense", at what level you want to explain things and the model you are using to explain things . At one level there are clearly only two: the present and the past. After that, as others have said, you can consider other things, call them tenses, and multiply the number.
It must be said though that the idea that English has a "future tense" is a bit hard to defend under any but the most basic model.
English has many ways of talking about the future, but no real "future tense".