Every time i fil the gas tank the gauge reads empty

You will need to test a number of things, the fuel gauge is part of a rather simple circuit.

Battery -> gauge -> tank sensor -> chassis ground to battery

If the circuit is broken at any of the steps, your gauge will read "empty". If the tank sensor is bad, it could read empty, or if the float in the tank has sunk, it will read empty.

I start at the gauge with a "test light" that glows when it sees battery voltage. Get a light at the connection to the gauge? Good. find the sensor connection, usually on top of the tank, accessible in the trunk. Probe with test light. Light on? Good. Connect wire to ground, gauge should read "full". If all that is as I said, then the tank sensor is bad. If you don't read battery at any step, you know where the problem is.

Could be faulty connection at the Tank or at worst you have to replace your sensor that goes into the tank

I think its time to change your sending unit in the tank,not sending a signal to the gauge

Looks like the sensor inside the gas tank is shot! It will need to be replaced. The tank needs to be removed to pull out the sensor and replace it....the empty light will work normally after that!

possible blowen fuse or a bad sending unit inside fuel tank also check the connections at the tank

when the tank is full the resistance is low so the power through the gage make is read full
as the tank empties , the resistance increases so the less current means the gauge reads less until empty there is little or no power , the gauge reads empty
simple check , turn the ignition off, no power , no gauge reading

float may be stuck up;Take tank unit out and check it with power on and observe the travel and relative gauge position.

chevy and gmc trucks have an on going problem with this,turn the key on,and get a rubber mallot or a hammer and hit the bottom of the fuel tank a couple of times,this will unstick something in the fuel pump/sending unit.

the problem is caused by a defective gas gauge sending unit, this part is located inside the gas tank, you must remove the gas tank to replace it.

fuel tank vent could be blocked by mud/pebbles etc, not letting the gas fumes escape while your adding fuel making it overflow, check underneath the car near the fuel tank .. something to start with..