Depends on the airline. For regionals, to my knowledge, there are no retirement benefits other than nonrev travel privileges. That's typically a hard ten years, especially to nonrev on mainline partner aircraft (ie overseas). There are often other requirements as well, such ten uninterupted years flying a fleet that's branded for that major partner.
For majors, I know some at least offer nonrev privileges after five years (and over a certain age, you can't retire at age 35 and get lifetime travel bennies lol).
Not sure about other benefits such as medical, that would vary by company, and pilot CBAs may specify different rules than those for non-pilot employees. IIRC only UPS/FDX still have pensions for new hires.
Best thing would be to ask in the forums for specific airlines, the devil is in the details.