Looking up information on generators, a low wattage gasoline generator (won't power your entire house) will on average use .3 gallons per HOUR.
High wattage generators (will power your whole house) use upwards of 1+ gallons of gas an hour. One high wattage generator that was considered one of the most efficient by several reviews i found on differing generator sites used 1.67 gallons an hour.
Also: Many sites recommended highly AGAINST gasoline high wattage generators because of the high cost, and reccommended going either natural gas or propane, because they're cheaper fuels.
Comparison of average home and RV generatorsAlso note that the REASON for the power grid is because mass producing electricity is much cheaper than individually producing it. In fact, the invention of the power grid is pretty much the sole reason we have such an electricity dependant society today.
Edit: You also say you pay $80/mo. for your electricity bill. You also say you pay $2.30 for gas. So $80/$2.30 = 34.78 (rounded) gallons of gas you have to use less than per month to save compared to your bill. If you ran your generator for a month, that's about 720 hours. so 34.78/720 = 0.048 gallons (rounded, again) of gas per hour you would need to use LESS THAN to save money over your electric bill.
As far as I'm aware, there are no home generators that are anywhere NEAR this efficient. The only way to save money with a generator is by SHUTTING IT OFF at every juncture you can. This kills off any extra power use while you aren't home/using it/whatever. However, this would effectively be the same as calling up the electric company and asking them to kill/turn on your power several times a day to cut excess Kwh usage, and this says nothing of the efficiency comparison.
Further edit: (sorry, i like math) Let's find out how many hours/day you would need to run to break even with the very numbers you gave us earlier. Assuming your generator is the max efficiency i could find (i.e. the lowest number) of .3 gals/hr, and we want to break even with your 80/mo. bill. So we know you pay 2.30 for gas, so 80/2.30 = 34.78 (rounded) gallons of gas per month to break even. So 34.78 / 0.3 = 115.94 (rounded) hours of electricity per month. We'll assuming just a normal 30 days/month, to give us the most amount per days on an average month (sorry, february, you freak!), so 115.94/30 = 3.86. To break even, you would need to run the generator (which at such a low wattage can't power your house fully) under 4 hours a day to break even.