Running an electric space heater off a generator is the most inefficient possible way to heat your home. You are converting fuel to mechanical energy and heat, just to turn it back into heat. You will use much, much more fuel than necessary per btu.
A portable Buddy or Big Buddy heater would be massively more efficient with no smell. Google is you friend on this.
Kerosene is also efficient, but stinky.
ETA: I just looked up the Portable Buddy heater. It puts out 4,000 btu's for 6 hours on low. That cost about $2.5 for 24,000 btu's, but cost is a very small part of the equation for emergency heat.
I am guessing that with my little generator that runs 9 hours on 1 gallon at 25% load would only run for 1/4 of that on full load, so 1500 btu's for 2.25 hours per tank @ $3 per gallon. That means with my little, very efficient generator I could produce 3,375 btu's for my $3 per gallon.