Fuel smell

My wife's Impala has reeked of gasoline for the past couple days. I finally had time today to give it a look and found this

The connector had traces of fuel around it, and a small pool under it so I fired up the engine and it began pouring fuel. Is this a matter of replacing a seal or will the entire assembly need to be replaced? When it comes to fuel systems I've never even changed a fuel filter, so guidance on procedures would be very helpful as well.