Typically gas costs LESS than electric. Gas is less efficient than electric, as others pointed out, more btus go up the flue than into the oil. However, in the end, your cost for gas will be less at the end of the year. Some things to consider, there are all types of btu inputs for gas, as someone pointed out. Go for higher input, better recovery, quicker cook etc, etc.
When I design a food facility, I will always choose gas over electric. If a manufacturer doesn’t offer gas, I switch manufacturers.
K