On a portable electric generator, do amps or watts have more impact on the time a device can run?

I have a small generator shaped like a soup can. It's basically a portable charger like for phones and tablets by USB, but it also has an AC outlet built in. My 1985 Squareview CRT can run on it for right at two hours before the generator dies, and the TV uses about 60 watts. My EDTV, a power efficient model... show more I have a small generator shaped like a soup can. It's basically a portable charger like for phones and tablets by USB, but it also has an AC outlet built in. My 1985 Squareview CRT can run on it for right at two hours before the generator dies, and the TV uses about 60 watts. My EDTV, a power efficient model using only around 25 watts however, runs for about one hour and fifty minutes and then the generator dies. However, while the CRT's wattage consumption is higher, it uses only 1 amp and the EDTV uses 2.1 amps. This leads me to believe that, although wattage is what determines how much power it uses and the money you'll pay for that usage, amps are what really matters if you're trying to figure out how long limited power can last. Is this true? Are amps the primary determining factor in this case?
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