a lot more information will be useful...like where exactly is the gas leaking from (you mentioned gas tank but didn't say that was where it was leaking) - in other words get up in there and get a good look (take pictures if you can)?

normally fuel lines are connected via a bronze or brass hard line that uses copper crush washers...this is on the fuel filter, charcoal canister, lines attaching to the engine, return lines from the engine back to the gas tank. Luckily I've never had to replace a gas tank or even a pump with my old crx so never had to learn how to do that or even disconnect the lines back there.