Either he or you [[1]] (has, have) to go.

Rule: When you connect two subjects using “Neither….nor, either…..or, not only…...but also, Or”, the verb should agree with the second subject.

In the above given sentence, the second subject word 'You' is a second-person pronoun. And the correct word to adjoin a second-person pronoun is 'have'. Therefore, the correct sentence would be - 

Either he or you have to go.