if it is a computerized machine i would not use it with a generator unless a surge protector will work also- you could fry some computer component if the electicity varies from strong to weak (brown outs)
if it is an older/vintage machine it would probably be a little safer. that's why i want a treadle- so when the lights go out...but i enjoy hand work so i just revert to hand stitching when the lights go out.