My father was an airline pilot for years (American, US Airways, and then Etihad) flying domestically and then internationally. I'd guess that if the airlines wanted to reduce pilot hours the pilot unions would have a lot to say about that.
Are they paid by the hour? I'd assume that pilots would earn an annual salary.
Most pilots do earn an annual salary. I'm not sure what the previous comment meant. Pilots simply have to work minimum number of hours per month, but the issue is that most pilots are now working up to the maximum number of hours therefore there are actually pilot union striking because of overwork!