The goal posts move according to supply and demand. High demand/low supply (a once in 20 year cycle) just a licence and functioning pulse will get you in.
Low demand/high supply (the other 19 years) the more space shuttle missions you have the better. A degree in rocket science will be a plus.
Whichever part of this 20 year cycle you are in, it's not the minimum that YOU have; it's more about what your competition has that determines your chances. Whether you have 400 PIC and 100 ICUS or 500 genuine PIC won't make much difference if the other guy has 200 total multi and 2000 fast jet time fresh out of the military and the airline is recruiting First Officers for jets.
From a GA operator point of view, having given you the induction ICUS and maybe even the multi rating in the first place, it would only seem good manners to acquire 500 PIC before moving on. Old school airline recruiters respect hours done actually as PIC rather than sham time which is what a lot of so-called ICUS on offer is (pay to fly nonsense etc). In a reasonably busy GA operation 500 hours would only be about a year of your life.
Mods will probably move this to the wannabe section, where you will find more pertinent comment from those who have been through the recruitment process, or are involved in it, or who have been sadly let down by pay to fly programs.