This question is an exact duplicate of:
In the sentence "the correct form here would be..", what does 'would' mean?
A: I've got a doubt concerning a statement to talk about the future: do we say the best student will win a prize or The best student is winning a prize?
Answer: The correct form here would be "will win". You would say "is winning" when you are describing the present - i.e. when you are watching the prize-giving.