In my case they didn't cancel my study permit, but I'm not sure about work permits.
Why not apply for PR since you have Canadian work experience? this stream is faster and it makes more sense because you've already spent at least a year in this country. It's a bit odd that you waited this long to claim that your life is in danger back home, unless you have strong evidence that recent changes happened there and it's not safe for you to go back.
If you think refugee is a faster route to PR, you are most likely mistaken. Look up different PNPs or FSW, the govt wants you to stay and you will very likely jeopardize it with a refugee claim but I won't know what situation you are actually in so good luck with whatever you do.
Yes your PGWP will be cancelled. Not sure why you ae choosing to apply for asylum at this point but it is incredibly risky. You should be focusing on working for a year in an NOC 0, A or B job. If you apply for asylum you are putting all the time and money you spent on your studies at risk. Is there a reason you have decided to apply for asylum at this point?