2002 Pontiac Bonneville smell of gas

check for a fuel leak in engine compartment. might be orings on injectors or fuel rail

It that a hard job to fix and about how much to fix it and would that be the reason for my check engine light to be on

if your check engine light is on that is probably the reason for the strong smell of gas. go to an auto parts and they can scan for codes to see what the problem is. they don't charge for this.