I netted everything out of a 40 gallon breeder live bearer tank once that was on the bottom of a double stand shut of the filters shut off the heaters. Do to work and maintaining my other tanks it sat for over 2 months with water and some hand fulls of java moss just sitting in it. when I went to empty it out i found 3 fry I had not seen still alive in that tank. They had not grown hardly at all but they were alive. I moved em to a community tank . Not sure what happened to the other two but one male sword tail is still alive and around an inch and a half long now.
Life finds a way unless us humans muck it up, Sometimes it still finds one even when we do.
So yes they likely can in small numbers survive but as said above live food is a bad way to go and why give the guppys a miserable life If your gonna keep em just get a 10-20g and let em do their thing if nothing else you get free food when they breed.