They are both pretty big celebrities. Obviously not as popular as star football players. Football is a religion in Brazil.
Anderson is the face of Burger King and Wizard (language school).
Belfort had some notoriety in the 2000's, when he was a participant in a Big Brother type show in Brazil. That's where he met his wife.
Anderson became very popular after his win over Belfort and the UFC became mainstream in Brazil. After his loss to Weidman, he became a little bit of a joke...
He needs to fight seriously to regain his respect on December 28th, no matter the outcome.