If a person has hep c antibodies but a undetectable pcr is it gone or can it be in the body dormant? can it reactivate?

Either is possible: Positive anibody test for Hepatitis C indicates only past exposure. Negative PCR means the virus is undetectable which means it is inactive for the time being but with no guarantee that it had completely disappeared

See below: If the patient has never been treated for Hep C the (+)antibody test is a false positive and does not have hep C. If the patient has been treated the (-) PCR indicates the patient has had a response to treatment and no virus is detectible. If the test is (-) 3-6 months after treatment ends it is a sustained virological response(SVR).99% of patients with SVR will remain so and are considered cured.