In fact, Benzema single-handedly caused Madrid to knock out PSG last week. Making a hat-trick against PSG in 20 minutes shows how good you are. If they hadn't had Benzema, PSG would have just moved on to the next round.
However, Benzema cannot do it alone. Without assists from 2 creative midfielders of Real Madrid (Kross and Modric) and wingers (Vinicius and Asensio), Benzema will be difficult to score. I think all players of Real Madrid have contributed to winning the match against PSG. Even Benzema can make a hattrick, Real Madrid will be defeated if they have weak defenders. So, we also need to appreciate how good the performance of Real Madrid defense line is, nowadays.