I have never heard of helicopters having ejection seats.
It’s an increasingly common feature on attack helis. The Russian Mi-28 has an ‘ejection’ system that’s really just an ‘assisted bailout system’ that lets the crew escape to the side and down. The Ka-50 and 52 have a true ejection system that blows the rotorhead (and thus the blades are flung away) then a second later after the blades are gone ejects the crew in the conventional fighter manner. It’s not quite a true zero-zero system but it’s as close as choppers are going to get for a while.
No US service heli has an ejection system, though we played with the idea in the 60s and 70s.