If this is really a matter of a legal test, then the NCAA has already lost, but you knew that before you even started the discussion. If Kain Colter is asking a judge if college football is a job, then it's over, because money in exchange for effort is typically granted the designation of work, and then by extension the legal and economic notion of "employment." It's hard to get around that in the end, and that is why the NCAA will be a forgotten, unloved corpse in the great pauper's yard of bureaucratic history.
But if he's asking you, the average human with a job, then we have a discussion on our hands. For instance, you probably want to know a few things about the position, and whether it is similar enough to yours to be considered a "job."
Q: Does college football have sexual harassment in the workplace?
Yes. Yes, it does.
Q: Do managers often seem to make rash decisions with no basis in reality, and yet still survive, and sometimes even thrive?
Q: Can the workplace become hostile?
A: The 2013 Florida football team
Q: Do people steal each other's food out of the break room fridge?
A: Yes, and there is even a special day for it called "National Signing Day."
Q:Are you forced to go to workplace events during the holidays when you'd rather do anything else?
Q: Is nepotism an issue?
Q: Are women underrepresented, and if so are they underpaid?
A: There is literally only one major female figure in the sport of in college football, and she is chained and forced to run naked in front of hundreds of people before every game.
Q: Does the workplace shirk safety standards and encourage workers not to report them?
Q: Do you have to show up even if you don't want to?
A: Yes, though technically every game Northwestern played in October was part of a volunteer scientific study. One day we'll conquer Minnesota-Iowa Wasting Syndrome.
Q: What about that dude who just won't stop cropdusting the whole office even though everyone knows it's him?
Q: Do child labor laws apply?
A: Yes, much to Lane Kiffin's chagrin. Phife Dawg's unborn grandson is ready to start today, dammit!
Concluded: It's a job.