What are typical kitchen supervisor salaries?

Do some companies pay a lot more for this position than others? What does a top earner make in this field?

What skills should you learn to increase your salary?

a culinary degree would help, but a lot of owners will want you to have real world experience. i didn't go to culinary school but it took me ten years to make it to managerial and my pay isn't going to be much higher ( maybe in a few years ). Normally a line cook will make any where from 10 - 25 an hour, depending on the type of line, the location of the restaurant, and who owns it or its prestige/notoriety .
A supervisor/manager or executive is a tough position, just like being a line cook or prep, you must stay focused and be alert. you can pull out a 30k-45k a year pay, but you have to be able to take the heat.

working as a dishwasher will get you into a restaurant, and up the ranks. be cool, be yourself, don't do drugs, and you will do fine :D