Dont try so many times (in a panic) in one sitting, you may be flooding the motor. Give it 15-20 mins between cranking attempts if you suspect that, letting the gas evaporate.
If you wanted to, (not reccomending, but it would prove flow) , disconnect the line coming off the fuel filter, having a friend hold a towel over it, and prime the car, seeing if it getting fuel at that point and nothing is clogged
Typically, mechanics/techs will tell you to never run the cars tank too low, being that solids can settle at the bottom of the gas tank over time. Now, one would be quick to say that there is a fuel filter that would stop such things from reaching the motor (both on pump, and in engine bay) , there is, however, these can still get clogged.