If i can smell gas with the heat on,

And see moisture on the top of the block i think? on the top left runs down towards the belt? Is this a fuel injector also? It isn't dripping out but there is a lot of moisture on top left side of engine and moisture runs down the side down towards the belt area. should i not drive? is it a fuel injector also? How much and what would you say 0-10 to fix this problem would be? thank you gents :-)