Office Space was released in 1999, at the peak of the dot-com bubble. So, of course office jobs (particularly software jobs) would decrease when that bubble popped.
I specifically avoided making the claim because you really cannot prove either way
I remember when it was released, I graduated that year, and I remember the reactions at the time
it would still be anecdotal and it's hard to know how many people did in fact resign as a result of the impact from this film, and if it's something that would make any difference in the grand scheme of things
But it's not as a result of that movie.