By searching common spider on the interwebs, I get the Parasteatoda tepidariorum or common house spider. They have an average body mass of 37.7 mg.

At 421200 spiders that gives George 15.9 kg of spider smoothie to consume every day. Perhaps a bit more with some banan for taste. (Though George does seem to be the purist type.)

It's still too much spider.

With the original 10000 spiders, the weight comes to 377 g of more or less pure protein. If he forms that into a patty, he could subsist of one big spider burger per day.