TLDR: about 1-2 isk/month seems reasonable for minimum wage workers. 3-5 seems reasonable for capsuleer crewmembers.
so i’ve actually done a surprising amount of thinking on this topic over the years for some reason, and i’ve come up with a theory that I (think) mostly addresses the question. Its entirely head-cannon, but I do pull from a combination of lore sources as well as some simple extrapolation. so strap yourself in.
to start with, lets make a quick distinction between station-dwellers/core worlders, and land-dwellers/outer worlders. much like in the real world, you have a huge amount of disparity of income between first world countries and third, with eve being a dystopia that disparity would be even more pronounced. so the chronicles and missions that refer to planetary currencies being effectively worthless compared to isk, or a handful of isk being enough for someone to retire comfortably mostly being in relation to poorer planets or ass end of no-where stations. much like in the real world where a couple hundred USD could be more money than someone might earn in their life in some impoverished nations.
now for a more realistic and useful metric, anyone who is working a capsuleer ship is going to be a station-dweller, maybe core worlds maybe null, doesn’t matter a huge amount since the disparity isn’t going to be quite as glaring as between planetsiders and spacers. we do know from the chronicles that living on a station is orders of magnitude more expensive even for the lowest rungs, similar to living in the heart of new York. so while for a baseliner a handful of isk would make their eyes widen, on a station, while it would still be a good amount, its more like “thats a couple months rent taken care of and maybe a few debts payed down”
Now for a bit more extrapolation, using the comparison of a shuttle to a 747 or a luxury jet or yacht in cost. in the real world a personal jet costs between 3 million and 90 million, so lets split the difference at 46.5 million. using average jita price for a shuttle we have 21,752 ISK. a touch of math later, and we have a ratio of 1 isk = ~2100 USD. or, approximately the amount that an unskilled worker would earn per month. (~13 USD/HR)
using those numbers, and if we assume that rent on a station is about the same as a city like new york (aprox 3k/month) just to survive there someone would need to earn 2+ isk per month, even working at their equivalent of mcdonalds.
crews on a capsuleer ship, due to the extra skills and risks involved, are probably going to be closer to 4-5 isk per month. which is a comfortable living if nothing to write home about. and most likely that rate is fairly consistent across ship sizes, possibly even going down the larger the ship is since while larger ships require more crew and more skill, they are also appreciably safer. (you earn more on a small alaska crab ship than you do on a cruise liner)
as for how crewmembers get paid and placed. I’ve always envisioned it less like having your own dedicated crew, and more like a temp worker sittuation, where the actual crewmembers are employed by the station manager and get assigned to ships as they get assembled according to their skills/position in line. with the money for those wages coming out of station taxes/market taxes etc. why bother running around, holding interviews etc when you can just contact the local temp office who’s already done the work for you and grab however many out of work and desperate people needing to make rent this month as you could possibly need.