Unfortunately SEALS don't have sgts rank as they're all sailors
this guys must have been a Chief Petty officer 'Chief'
Or they weren't actually SEALS... or someone is making up porkies...
Of course, a plain, ordinary Sgt is an E-5... same as a Petty Officer 2nd Class.
A Staff Sgt is an E-6 (PO1).
It takes a Gunnery Sgt (USMC) or Sgt First Class (Army) to equal a CPO (E-7).