Ok, plenty of people have commented on the effects of HCI on metals and plastics. Forget about that. If you ruin a GF, you are out a few grand. That is meaningless in the big picture.
Consider that chlorine gas was used as a chemical agent in the first world war, and horribly crippled or killed vast numbers of soldiers who came into contact with it. While it is unlikely that you will be able to release enough to expose yourself to the same doses that that they encountered unless you were deliberately being unsafe, why would you take chances? Your health and safety are far more important than a GF, do not take foolish risks and play with fire.
A minor quibble: Burning plastic with chlorine doesn’t release never gas, it would release hydrogen chlorine gas (HCI), which is an dangerous irritant, but not a nerve agent.
If you really feel a need to cut PVC, a milling machine might be a better choice since it doesn’t melt or burn the material.