It depends on how much electricity costs in your area per KWH and how much your gas rates are.
But for an electric dryer it usually costs around 41 cents for each load of laundry to be dried
And for a gas dryer the load of laundry usually costs 33 cents per load.
So in most places a gas dryer can be cheaper to run but it depends on the cost of natural gas in your area and the cost of electricity in your area as to whether it will be cheaper to run the gas dryer vs an electric dryer.
Where I'm at it would be cheaper to use a gas dryer instead of an electric dryer to dry clothes.