Yes, you are right the ranking is done for all the applicants in the pool. Whenever more than 1 applicant is stuck on the same CRS (tie situation), the applicant with the oldest profile among them is ranked highest among the tied folks.
But it does not matter unless your CRS matches with the CRS cut off for a draw.
Let's assume, there were 3 applicants on CRS 475 with ranks 1801, 1802 and 1803 before today's draw. They would be ranked as below based on the profile creation date:
1801 - CRS 475 - Sep 5, 2017
1802 - CRS 475 - Oct 5, 2017
1803 - CRS 475 - Nov 5, 2017
As 2000 applicants were selected, all 3 applicants get ITA. The ranking order is irrelevant for all the above 3 applicants as all 3 get ITA.
I beg to differ here. As CIC has mentioned clearly in the example, it could still be a possibility that a candidate with higher CRS than cut-off will not be issued ITA if he submitted his profile after the final candidate (2000th).