CaliGuy
Banned
What about if the Bolsheviks merely retreat as far back as they can? Would Germany be able to occupy all of Russia up to the Pacific Ocean?According to Tooze Ludendorff had German and Finnish forces ready for just that in Summer 1918, but the politicians didn't want to break with the Bolsheviks until victory on the western front made it safe to do so. But nobody in Berlin wanted the Bolsheviks in power permanently. They were viewed as a bunch of murderous savages - as indeed they were. As soon as Ludendorff's hands were free it would be game over for them.
The Germans were within striking distance of Petrograd and Moscow in a way the Entente never were. And as David T notes, lf a handful of Czechs could take over the whole of Siberia, it's hardly likely the German Army would have any problems. After all, even OTL Kolchak was able to penetrate European Russia as far as Kazan, so once the Germans are in Moscow the Bolsheviks don't have many places left to retreat to.