Is have a collective noun?

No, the word 'have' is a verb (have, has, having, had), meaning to possess, to own, to experience.

A noun is a word for a person, a place, or a thing.

A collective noun is a noun used to group people or things in a descriptive way.

Examples:

My mother made a pie. (the noun 'mother' is a word for a person, the noun 'pie' is a word for a thing)

My mother made a batch of pies. (the noun 'batch' is a collective noun used to group a number of pies)

We will have pie for dinner.