My car smells like gasoline, After turning it on! What's causing it to smell?

you should check under the hood with car running to see if you can find a leak somewhere if you cant find a leak you better take it to a shop and get someone to check it out as soon as possible

Beside checking under hood, you also need to check the fuel pump connection, which is in fuel tank, normally you can check the connection under your rear seat.

Is your check engine light flashing? If so, do not try too drive the car, have it towed to your repair place. Leaking injector(s) could be the cause.