Can fentanyl cause a patient to have amnesia?

With benzo: Fentanyl is usually given with a benzodiazepines like versed for sedation and the benzo usually causes the amnesia. Fentanyl by itself does not cause amnesia but can cause confusion.

Yes: Fentanyl is a very potent opioid analgesic. While not a pure amnestic drug like a benzo, with high doses and sedation you most definitely can have amnesia.