Sometimes at ignition on the guage will read empty, the electronic display will also read empty the fuel warning light will also be lit, however during the course of driving the fuel gauge will begin to creep up, the warning light will go out and the electronic display will creep up in sympathy with the analogue display until both reading are correct for the amount of fuel in the tank
The fuel level float may be sticking for some reason. Have the trouble codes pulled and see if anything comes up first. Any Auto Zone or Advance Auto will do this for free. Then you will have to have the fuel level float assemly checked if no codes for the sensor come up.