The Cameroon forward signed a one-year contract at Stamford Bridge during the summer and has recently been linked with a return to his former club Real Mallorca.
However, when asked if the 32-year-old was certain depart, Mourinho replied: "Of course not. He's a big player, even if he doesn't score 25 goals, because his contribution to the team is very high. We are happy.
"He plays for titles. He decided to come here to the Premier League, to Chelsea, so Samuel is enjoying his career until the end. We'll see what he wants to do at the end of the season.
"Maybe he wants to go to Real Mallorca, as he promised his son. Maybe he wants to stay with us, or go and finish his career at Inter. He doesn't need titles, he doesn't need money."
Eto'o has scored eight goals for the Blues this term.