Yes, you see this all the time in non-live chess. The ratings calculations are done with whatever the current ratings are, not what they were days, weeks or months previously. See this thread.
I seem to recall having seen people complain about extreme cases where the ratings changes from start to finish of a tournament are so large they end up losing points from winning games but I can't put my hands on the thread right now.
Hi,
If I am playing with someone with a rating of 1400 and taking into account my own rating, if I win, my rating will improve for example by 15.
Then, if that person is simultaneously playing 5 other matches that end before my game with that person ends, therefore changing his current rating, will that affect the amount of points to earn vis a vis what was initially determined (15 in this case). Thanks.