My 2017 had 20% fuel filter life when I bought it, I ran it down to 0% and changed it.
I bought it 12/29/18 with 10,345 miles and 401.3 Hours, 20% Fuel filter life.
Fuel filter changed @ 0%, (5/13/19) 12,852 miles and 522.4 hrs.
I currently have 17,336 miles and 796.3 hours with 58% fuel filter life remaining on the DIC.
I've put 6,991 miles and 395 hours on my truck since I bought it. I used 20% on the original filter and I'm down 42% on the current one. That's 62% fuel filter life used since I've had the truck.
I keep a fuel log, I've ran ~686 gallons of fuel through the truck in 6,991 miles and 395 hours.
If the fuel filter life is calculated by gallons used, then in my case 11.07 gallons used represents 1% of fuel filter life.
If the fuel filter life is calculated based on engine hours, 1% fuel filter life is 6.37 engine hours.
If it's based on miles, in my case 112.76 miles represents 1% of fuel filter life.
I calculated this based upon my usage and records on the truck since I bought it. If you calculated it based upon the first 80% of fuel filter life from before I bought the truck, I'm sure you'd get something different.
I do know that you can see actual fuel pressure and commanded fuel pressure on a good scan tool, so maybe the ECM can monitor or calculate the fuel filter life based upon the fuel pressure/flow drop over time. It would be interesting to know, that's for sure.