Yes, Medicare is a qualifying health insurance plan for employees to be reimbursed through QSEHRA.
Remember that in order to participate in the QSEHRA, you must have health insurance that qualifies as Minimum Essential Coverage. With Medicare, either Medicare part A (Hospital Insurance) or part C (Medicare Advantage) will qualify as MEC.
As long as you have either Part A or C, then you can also claim reimbursement for all other parts of Medicare including Medi-gap coverage .