If I understand your post correctly, it sounds like you are working for a startup where people consistently work 9 or 8 hour days (or less). As someone who has worked as a developer for 15 years (in both startups and large companies) and who has also started my own successful company and grown it to a market leader, let me share my opinion on how startups work. Remember that the vast majority of startups fail. To make a startup successful, you need either:
(a) An incredible amount of pure dumb luck and good timing (very rare)
(b) A little bit of luck PLUS an incredible amount of hard work and dedication
If you go to the owner of your startup and say "We will work harder if you pay us more", that indicates that you don't have the intrinsic drive needed to make a startup successful. If on the other hand you go to the owner and say: "Listen, we are going to work as hard as humanly possible to make this successful. We'll work all nighters, 18 hour days, whatever -- we will do what it takes on a consistent basis, making sure that we don't get so burned out that we're making bad decisions or doing poor quality work. In return, we expect to have ownership in this company [aka stock options or even better, a straight grant of common stock if you can negotiate it], to be compensated well, and to have a productive work environment. We don't need rules on minimum hours per day -- in fact if you need these rules to make people work harder, we probably have the wrong people on the team."
If you're not willing to get on board with that, you don't have what it takes to make a startup successful and you should seek work elsewhere. If the owner of the company is not willing to get on board with that, then HE (or she) does not have what it takes to make a startup successful and you should seek work elsewhere.