Gas can be "put" into a place by several ways.
Since gas responds to pressure differences, if the pressure drives the gas from place to place, you can say that the gas flows into a container. There is no passive form for that, but you can say the gas is driven by the pressure.
If you use a pump to force gas into a chamber with a high pressure, then you pump or force the gas into it.
Another verb, used especially when the container has no gas initially, is fill. You can fill a balloon with gas or fill gas into the balloon.
Note that in your question you assume that pour is used only for liquid, but you can also pour some solids that are granular, like sand, sugar, or wheat, and technically you can pour a heavier gas into a container which holds a lighter gas. Pouring literally describes filling using gravity, and metaphorically can mean any flowing movement of substance or entities.