One advantage to having a gas fireplace is the ability to manage the unit in the event of a power failure. Electricity is a remarkably small part of a working gas fireplace. Many modern units have a battery-powered backup system for igniting the pilot light. If your fireplace has a continuous pilot light, the power outage should not affect its function. However, if you have a element with an intermittent pilot, it may be necessary to trigger the pilot manually when the electricity is off.
Turn on the gas valve that supplies the fireplace, if necessary.
Search for the knob that ignites the pilot light. The location varies based on model. If you do not see the knob on the outside of the unit, look for a removable panel. Some manufacturers secure the ignition switch under a panel. The switch may be labeled "Pilot Ignite" or "Ign." The panel may slide off or require you to remove the screws with a screwdriver.
Shine a flashlight on the knob and turn the knob to the "ignite" setting.
Press down on the knob while it is in the ignite position. Hold the knob until you hear clicking. This indicates the system is sparking the gas to light the pilot. Release the knob when you hear the clicking but maintain it in the "Pilot Ignite" position. Some models may require you the hold it after turning to the setting. Wait 10 seconds for the pilot to light. If no flame appears, wait 10 more seconds and press the knob again to spark the unit. It may take more than one try to light the pilot. At times, air builds up in the gas and pressing ignite dissipates it. Once the air is out, the pilot should light.
Turn on the fireplace as you would normally. Once the pilot light is on, the unit should operate without electricity.