Do barbiturates (I know they're rarely used) cause amnesia in higher doses like for sedation or status epilepticus, like benzos or other gaba drugs?

Depends on dose. Barbiturates can be used to sedate someone mildly but they can also be used to produce a very deep anesthetic where the person will not only be amnestic but will be very deeply unconscious as well. It is all a question of the dose administered.

To be more direct - yes, barbiturates can be used to produce amnesia. .