The Ghost Rider Skin is a Marvel Fortnite Outfit. This cosmetic has been leaked, and the skin will hopefully be available to purchase in the near future!
Ghost Rider has not yet been confirmed as a skin, but there's strong evidence due to a Marvel alternate comic book for Venom #29 that he will likely be an outfit in Fortnite.
How-to Get the Ghost Rider Skin
Ghost Rider was leaked or datamined, which means we don't know for sure how it will be released. Most cosmetics that are leaked will be released within 30 - 60 days of their discovery.