Can an electric dryer be next to the gas furnace?
As far as I know, as long as the electric and gas lines don't actually touch, there's no more reason to be concerned about the gas and electric being 2 feet apart as there is 20 feet.  

If you have a gas leak from the furnace, the furnaces own ignition system (pilot light or electronic sparker) has as much chance of setting off a blast as the dryer.