What happens to helicopter pilots during an emergency?  Do they have ejector seats like in jets?

No, helicopters do not have ejector seats because they would eject the pilot into the helicopter's rotor system.  During an emergency or other loss of power, helicopter pilots auto-rotate.  Auto-rotation is the decoupling of the rotor system from the engines to allow upward air flow to drive the rotor system at a faster than normal rate, providing kinetic energy that can be traded to arrest the helicopter's rate of descent.  To initiate auto-rotation, the helicopter pilot flattens the pitch in the rotor system's blades, reducing drag, and allowing the upward flow of air to drive its rotation.  When the helicopter is 100-150 feet above the ground, the pilot will then aggressively increase the pitch of the rotor system's blades, temporarily increasing lift and cushioning the helicopter's landing.