Engine cranks but will not start

Clearly this is a fuel issue if it starts with starter fluid. However, we need to start with checking the pressure to find out if we are even getting the proper pressure.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Without knowing this we are guessing at the next possible thing but that is assuming you didn't already replace the faulty part with another faulty part. You have already replaced all the likely suspects so we need to confirm that you didn't already fix it but just replaced it with another bad part.

Unfortunately it happens too often that we have faulty pumps so that is what I am expecting this is.

Let's start with this and go from there. Thanks

We've already had 2 mechanics look at the car that haven't been able to determine what the issue is. One of these mechanics did check the pressure and didn't find any issues there aside from having to change the battery because there wasn't enough power. The fuel pump is new however how can it be determined if it's a faulty fuel pump?

Did you also replace the fuel pump control module under the left rear seat? From your description it sounds like the pump isn't engaging to prime the system, but once the engine starts running and the ECU gets an oil pressure signal the pump starts working. You may also want to check if the inertia switch in the passenger cowl area has a problem. It can also shut off the pump to keep it from priming.