Here we go.
Ronaldo have played 4313 minutes this season, which translates to 47 x 90 & 83 minutes.
Neymar have played 3744 minutes this season, which translates to 41 x 90 & 54 minutes. (6 x 90 & 29 minutes less than Ronaldo).
Neymar, with his 37 goals in 3744 minutes, currently have an average of 0.89 goals per 90 minute. NOW, if he was to have played the same amout of minutes as Ronaldo, then he would have snatched up 43 goals, by this point in the season. BUT, it doesn't end here! If we were to apply Ronaldo's penalty goals too, then Neymar would be at 54 goals at this point in the season (Ronaldo scored 12 penalties, but because Neymar already scored one earlier in the season, I have decided only to add 11 of Ronaldo's penalties).
So there you have it, Neymar could very well have had 54 goals at this point, with 4 games to go.
*Note
He could even have scored more, seeing as he probably would have scored a few freekicks, had he been the one to take them. (like Ronaldo)
We can actually take this a step further, because the total of minutes Neymar could have played this season (excluding 2 x Huesca & 1 x Elche in Copa del Rey), would have been 4770 minutes. Had he played 4770 minutes and kept his 0.89 average, then he could have had 47 goals now and 58 with Ronaldo's penalties.
With enough minutes, penalties & freekicks he could very well have had a 60+ goal season and he JUST turned 23. !
btw, I am aware there is A LOT of maybies in my post
Cheers