PS3 probably realizes what a disgrace to the movie that game is.
...Sorry. I have the Wii version myself, fun game but too much killing for it to be faithful to The Godfather. No Corleone would just barge into a warehouse and kill 50 men single-handedly ffs, they didn't roll like that!
Anyway, surface scratches are never a culprit with PS3 games; Blu-ray discs have a special coating on them because the discs without it were very suceptible to scratches (this was before release, so no it wouldn't effect your game). There's a video of a guy on Youtube taking steel wool to one and it still playing afterwards. Either you've got a very deep scratch on it, or there was just a problem with the manufacturing of that disc (unlikely if you've already played it though).
When you say won't read at all, do you mean the PS3 doesn't even know it's in there (ie. the disc icon doesn't show up in the XMB when you put the disc in) or does it recognise it but won't load when you click play?