Why does dry HCL gas does not have any hydrogen ions?

DryHCl do not contain any water, so do not get ionize, but in the presence of a drop of water, HCl is ionized and release proton, that turns blue litmus to red

Dry HCl gas doesn’t change the colour of the dry litmus paper because acidic behaviour of acids due to the presence of hydrogen ions. The acids produce hydrogen ions only in the presence of water. So, in the absence of water, a substance will not form hydrogen ions and hence will not show its acidic behaviour.