I have a 2000 toyota corola, when you turn it over or start it, it leaks a lot of gas from on top of the tank and runs dow all over, what is the most likely cause, fuel line leak, fuel pump, or something else ?

I've seen a lot of rodents get up there and chew through the plastic lines. Could be minor, or a complete tank. Don't know until it's inspected. Way to hard to tell from here.