Provided you are at or above EY's baseline standard, then of course less people turning up helps you. If there are 200 people above this level, but EY are only taking on 100, and you are ranked the 150th 'best', then you will not be making it. If half the people turn up you can crudely say there will be only 100 people above the standard and that you will be ranked 75, you will then be in the 100 EY will be taking on.
That said, to be above EY's standard you can bet you'll have to be motivated and have great determinations. Something that those that didn't turn up might not have.