I do know that giant rats actually do exist. Look at this giant Mallomys rat from Indonesia:
That sucker must have a total length (including the tail) of over 3 feet, and it is one of the largest living rats. Then there are the giant pouched rats of Africa, there are several species, and they can reach 2 and a half feet in length. They kindof resemble dogs more than rats:
They are also easily tamable and are often kept as pets. Then there is the largest living rat of them all, the cloud rat of the Philippenes. They more resemble giant squirrels than rats:
Those guys can reach 4 feet long. The World is full of enormous rats living today. But no rat living in the wilds of the USA has ever reached those proportions. Though some people say different. Some on that program have claimed they have seen rats as big as cats or small dogs.
There is no doubt in my mind a rat can fight off a person given the correct opportunity. They are tough little buggers! They may can even kill babies as claimed in that program. Who really knows what a giant, hungry rat would do?
My personal feelings on this issue? I love rats! I think they're very fascinating animals!! I've had pet rats that were as affectionate as dogs. But I highly doubt there are rats as big as dogs living in New York. Some homeless people I would have a tough time taking their word for the gospel, a lot of them are homeless because they drink or drug their money away. But if I ever do see a giant Norway rat that was claimed to be seen by some of the witnesses on that program, I would turn and run the opposite way! Norway rats are so aggressive, they have even been known to kill other rats. That's why you usually won't find Norway (or brown) rats and black rats inhabiting the same space. Norway rats can easily make short work of black rats! They are not really afraid to stand and fight against a human if the opportunity arrives.