An embodiment of a system for measuring fuel ignition within a torch igniter for a combustor in a gas turbine engine includes a housing surrounding and defining a combustion chamber, a first glow plug received through the housing, and control circuitry. An innermost end of the first glow plug extends into the combustion chamber while an outermost end opposite the innermost end extends away from the combustion chamber. The control circuitry is connected to the outermost end of the glow plug and is configured to measure a temperature of the innermost end of the glow plug based on electrical resistance of the glow plug. The control circuitry is further configured to determine an operational parameter of the torch igniter based on the temperature.