IF Pilot is remaining lit, Thermocouple is fine. Blower motor coming on verifies main voltage (120vac) and low voltage (24vac).
That also verifies the transformer.
IF your GV is getting 24-28vac, check burner orifice, burner tube for blockage (spider).
If all clear, need to have gas pressure checked.
IF GV is not getting 24vac, test across t-stat R and W, should read 0 vac with call for heat.
Take care and best wishes,