The fewness of the saved has long been a doctrine of the Faith.
I assume hell will remain empty until the Last Judgment. Once occupied, its residents will lock its gates from the inside.
Those who contend that hell will remain empty are blithely ignoring the entire point of this life: to identify with certainty those who want God to be their boss eternally. Most don’t.
Everyone chooses either Hell or to be in state of sanctifying grace when they die.
A good book recommended by Patrick Madrid “The Dogma of Hell” By Fr F.X. Schowppe Tan Books
Explains basic catholic doctrines on Hell, recounts numerous true stories that reinforce belief in Hell.
Read the Gospel of St Luke 16:19-331 about the rich man and Lazarus.