no

The first sentence is fine. One implication is that someone/some company has made a lot of money selling you something. The use of "off" in the second sentence is confusing and not natural speech. Without the "off" - "They have made millions because of me" has a different meaning from the first sentence. It can imply that you did, or provided information, or you helped make something happen that resulted in creating millions for someone/some company.

They have made millions off of me. The second choice is incoherent.