Probably need a generator. Any large TV pulls a lot of power. Say around 200W means most UPS would only run for 30 minutes on typical small battery packs. Don't know much about a FIOS but if that wants say 30W more it doesn't help.
You're talking serious power reserves there, like a pro-grade UPS, i.e., big bucks.
Check out APC, they have made UPS/conditioner systems intended for home theater use, but I believe most of these will typically only give you 5-10 minutes of backup unles you add extended battery units. Don't forget that these batteries also tend to crap out after a few years and will have to be replaced - this will add substantially to the overall cost, especially for a sytem with the kind of power reserves you're looking for. Waste of money, IMO, for the rare occasion you may need it. A generator is the wise choice, as posted.
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