Pumping the pedal doesn't do anything. You don't have an accelerator pump like a carburetor to force gas in.
Try just turning the key on, wait 5 seconds, turn it off, then on again. Should start right up without touching the pedal. You may have to cycle the key one or 2 more times. The worse it gets, the more times you'll have to cycle it.
It's the check valve in the fuel pressure regulator on top of the tank that's going bad. It allows the fuel to drain back down the fuel line back to the tank.
When you first turn the key on, the pump only runs for 3-5 seconds, then stops. When the regulator is going bad, it doesn't get fuel all the way back up. Then when you crank it the pump runs again, eventually getting fuel up.
When you pump the pedal you are only letting in more air to the cylinders, making it too lean when the fuel finally does get up there, making it even harder to start.
The computer knows how much air and fuel it needs to start, let it do the thinking by keeping off the pedal.