Hi,
First:
Do you want to know peak current or average current?
* peak current determines switching speed. Peak current often is not determined by the switching device, but the driver circuit.
* average current in most cases is not much informative, mabe to calculate VCC current (only useful for very low power applications)
If there is low peak driving current, then V_DS rise and fall times will be higher causing increaed overall power dissipation.
Qg: simplly have a look at Figure13. It clearly says "V_GS" and not "V_GS_th". And you see that it depends on V_DS (miller effect)
Average current is: switching_frequency * total_gate_charge. independent of duty cycle.
*****
I assume you need to look for basic informations:
Every MOSFET and IGBT manufacturer and every driver_IC manufacturer should provide application notes on how to design and calculate driving circuits.
Read through them. In a forum we can´t give more detailed and more complete informations.
Klaus