Yes, it will evaporate at a reduced rate.
However, it will still evaporate (until the temp is what?, 40 or 50 below F) because the vapor pressure some of the gasoline components is higher than atmospheric pressure.
When I was a kid, we would occasionally have a tractor or mower or some other machine that stood unused for 6 months or a year or more. This was back in the day when the fuel caps allowed the tank to vent to atmosphere; they simply had a hole in them. When we went to start it, we would have a problem because the fuel wasn't the same anymore, it was thicker and foul smelling, and wouldn't ignite properly in the engine.
Our farm fuel tanks used to just have a cast iron cap that didn't have any type of pressure seal. The local fuel company went around in the 60's selling everyone a pressure cap so that the tank would maintain a pound or two of pressure, to keep the more volatile compounds from evaporating before we used the gasoline.