Of course trucks are better than horses, otherwise we would still be using them. That applies to Russian winters, too. In that case, the issue is not about a generic truck being better than a generic horse. One has to ask, what kind of truck and what kind of horse.
A truck built for the French road network and climate, with its parts seriously worn down by the summer's campaigning, and sporting lubricants for the French climate, is obviously worse – in Russian winter - than a Panje locally-grown pony-sized horse; just like a large-sized, more powerful and faster central-European horse will be better than a small, less powerful and slower Panje horse, save in the Russian winter.
But all of those will be bettered by a truck specifically built to work in the Russian winter, with suitable metals, fuels, lubricants and tires employed.
So the point is making do with what you have. If you have one of those French war-booty trucks, you are better off with a few locally commandeered Panje horses. But if you have a serious, brand new, all-weather truck, you are better off with that than with an old, fair-weather French truck, a central-European horse, or a local Panje horse. All of the time, including winter.
As to German logistics allowing the capture of Leningrad, Stalingrad and Moscow, trucks do supply armies fighting block by block in cities, but don't do the actual fighting. If both sides are in supply, it's not a given that the Germans win in that kind of street fighting.
As to the choice of gas engines over diesels. A diesel engine providing the same output in kWs as a gas engine in the 1930s was almost twice as much heavier and bulkier. Which is much of an issue if most of your tanks are on the light or medium-light end. You can have lighter, smaller diesel engines if you throw money at them (just like you can have, however, much, much lighter gas engines by the same means).
On the battlefield, diesels are less likely to catch fire. OTOH, they have longer start-up times (which, for a combat vehicle, can be deadly) and less acceleration.
Finally, yes, fueling diesels would be easier in a war lasting years. But Germany went to war on the assumption of a quick Polish campaign (right) which would not bring other combatants in (wrong), followed by a quick attack on the SU that would bring down the whole rotting hut (wrong wrong). No sweat...