Most airliners use FMS (Flight Management System). The system icorporates aircraft performance data (fuel flow, etc.) with navigation. I believe the system can use multiple sensor inputs for navigation to include VOR, DME, INS, LORAN, or GPS. A pilot type person may have more specific/detailed explanation.
I am assuming most aircraft are using GPS for NAV these days. But that is just speculation on my part. It is true that not all air carriers have GPS capability. But most with FMS can do GPS procedures if they are RNP capable.
This is getting way to technical for me.