Helium is almost all captured from gas wells by cryogenically liquefying the nitrogen out of it. I guess you could do technically do that with the fab's air but it is a LOT of volume of air to liquefy and likely costs more than even inflated helium prices.
Most helium from most wells is simply vented because it is expensive to separate even with its relatively high concentration, and I imagine even the best case scenario for capturing it from a fab has abysmal concentration of helium. But because most of it is vented it also means if the capital is put down to build more helium separators on gas wells it wouldn't take long to increase supply. Short term for a year or two it can be a problem, but beyond that it is simply a cost versus demand issue. There is neither a technological nor source limitation, it is a pure capital investment limitation.