It certainly would have been of great importance to Germany symbolically. As to whether it would have caused the Soviet Union to fall, in my opinion, almost certainly not. There was still the majority of the Soviet Union for Germany to conquer after taking Moscow, and considering that the complete destruction or taking of every major western Soviet city didn't cause them to be defeated, it's unlikely that Moscow would have been the tipping point.

Indeed, if my memory serves me correctly, Stalin made plans to leave Moscow and move his command elsewhere, and only didn't do so at the last minute, which at least means he would have kept up the fight.

The US could make up for any lost industrial power through lend-lease, and even discounting that, as far as I've read, the general historical consensus is that even if the Germans had reached the Ural mountains, the Soviets would still have been able to keep fighting.

Anthony Beevor has really good stuff on WW2 in general, btw, and I highly suggest giving any of his books a read

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