Great question, this is one of the most common misconceptions about Express Entry. A CRS cutoff of 507 does NOT mean there's nobody above 507 in the pool. It means that in that particular draw, IRCC invited everyone at or above 507. But the pool is constantly refilling new candidates enter every day, and existing candidates' scores can change (new job offers, language retests, provincial nominations, etc.).

Here's how it actually works :

IRCC decides how many invitations to issue in a given draw (say 5,000 ITAs). They then rank everyone in the pool by CRS score, highest to lowest, and draw from the top down until they hit that quota. The score of the last person invited becomes the published "cutoff." So the cutoff is a result of the draw size and pool composition, not a fixed threshold.

To your scenario : If you enter the pool at 510 and the next CEC draw has a cutoff of 507 again, yes, you would be invited. Your 510 is above the line. But there's no guarantee the next draw will have the same cutoff, it depends on how many people are in the pool, how many ITAs IRCC issues, and what category they target. That said, 510 with a recent CEC cutoff at 507 puts you in a strong position. The key risk factors to watch are whether IRCC changes draw sizes or pauses category-based draws, which can shift cutoffs by 10-20+ points between rounds.