He might be already, it is a difficult discussion and will open a can of worms on a thread which is dedicated to Ronaldo. Put simply..
Maradona, Pele, Di Stefano, Puskas, Beckenbauer, Cruyff, L. Ronaldo, Platini, Garrincha, Romario, Van Basten, Zidane, Eusebio, Baresi
I'm sure I missed some names out here (ones in bold are definite top 10 material for me) but it isn't that easy to compile a top ten let alone put someone as the GOAT based on just 2 CL wins in which he didn't really star in both finals, but yes he scored mind you. There is also Messi to compete with too. I think both can cement their names in the top 10, they might already be in there but for me I'd rather wait until their careers are over.