Since people can make a living out of mountain hiking, how much would they get paid

not a huge amount.
alpine guides probably get paid about the same as ski instructors, ish.. there is less demand but there is less supply (because it is so hard).
winter guides would get paid a bit less (because you do not need as many qualifications).
porters get paid pennies..

most guide services pay around $10-12/hr. If it is a summer gig then they sometimes provide room and board. so summer jobs are decent.

l was getting paid $175 - $200 per day as an assisant snowshoeing guide in Calgary, AB, Canada. These earnings are normal for this part of Canada.

not much, l had a job in an outdoor pursuits centre in wales. the pay was a bit rubbish, but if your passionate about it then you can still live off it. try and find somewhere groovy and new:P