Failing his "legal" challenges, he will stand on the 5th. He is not just tangentially involved in the coup; he is the primary tool necessary for a possible successful coup. I think he will therefore apply a self incrimination defense in order to not answer any questions, and especially those which would implicate Trump as alleged de facto leader of the coup.

There is a whole quantum level of dishonesty among a large group of Republicans when Democracy is on the line.