The Catholic position on whether or not anyone is definitely in hell is very much a complex one, and a matter of some considerable debate, even among orthodox theologians.
The answer is tricky.
In principle, hell might be empty.
However, given some of the statements of Jesus, it would seem to imply that there is likely someone there.
The Catholic Church often claims that individual people are in heaven.
These are the people that the Church calls saints, and Catholics are obliged to believe that the saints are in heaven.
However, the Church has never made any such comparable statements about whether or not there are people in hell.
Even Judas has never been declared to be in hell by the Catholic Church.
No matter how wrong someone has behaved, we are obliged not to judge, in the sense that we may never condemn anyone to hell no matter the evidence.
In principle, everyone should be able to go to heaven.
Since heaven is available to every individual, it is therefore at least possible that everyone might accept that call to sanctity.
As a result, Hans Urs von Balthasar, John Paul II's favorite theologian, argued in "Dare We hope?" that it is at least possible that every single individual might be saved and go to heaven.
On the other hand, however, we do have some evidence that, although in principle everyone might go to heaven, we do have some statements of Jesus that imply very heavily that, as a matter of fact, not everyone does.
Jesus says there "will" be weeping and gnashing of teeth, not there "may" be weeping and gnashing of teeth.
Many of his statements about hell are put in this same, future tense.
In addition, Revelation seems to imply that at least some people will be judged badly at the end of time.
This is the source of the debate.
On the one hand, it is in principle possible for everyone to be saved.
On the other hand, we have some evidence that not everyone will be.