How many have been found to be immune to hiv?

Very rare: A very small minority of people have a mutation which makes it much more difficult for the virus to gain entry into the cell and establish infection. But even these people are not completely "immune" and can still become infected under certain circumstances.

Nonprogressor: There are people, rarely, who are long term non-progressors who do not require medications to control the HIV. We do not understand the mechanisms in these cases. It may be that the virus they have is defective....or that they have a component in their immune system that neutralizes the virus.