Can not having gas cause a car not to start?

You are correct. If you have no fuel, there is nothing to combust in the internal combustion engine under your hood. If you suspect this is the case, you can use a bit of what is called starting fluid to see if you car will fire and begin to run. Starting fluid is sold in small spary cans at any auto parts store, and it is fairly cheap. You spray a good shot into the air intake and try to start your car. As the starting fluid hits the intake manifold and is taken into the cylinders, the engine will "try to start" but will not run. This is an indication that you have a fuel problem.