alt Hacker NewsNope, as also mentioned in TFA, copper has a too great thermal expansion coefficient in comparison with glass.
If vacuum tubes had pins of copper, the glass-metal joining would have cracked very soon during normal usage cycles, and there would have been no vacuum left in the tube.
Real vacuum tubes and gas tubes had pins made of kovar, which is a Fe-Ni-Co alloy with a TCE matched to a certain composition of borosilicate glass.
The kovar pins were normally plated with nickel on their external parts, to enable soldering, because molten solder does not wet kovar.
Right, point being that metal-glass seals are very effective given the right materials. This has nothing to do with how the tube is evacuated, and there is never a point where the wires have to be "passed through the glass without letting air in."