Russia's population today stands at just under 150 million people, but that's only after a very chaotic and violent 20th century for that country. Between the First World War, the Russian Civil War, oppression and famine under communist rule, and the Second World War, tens of millions of Russians died in utterly preventable political catastrophes during the 20th century.
Assume things had gone down differently. Say that the Entente had won an early and decisive victory in the First World War. The monarchy survives and, despite periods of political turbulence, the empire slowly reforms into something remotely resembling a liberal democracy by this timeline's 2018. While Russia still gets involved in several wars, some of them quite bloody, none of them result in nearly as massive civilian losses as those suffered in WWII.
Fill in the details however you like, but here's my ultimate question: without a 20th century nearly as catastrophic for Russia, how high would the country's population be by today? For the sake of this discussion, let's assume at least Belarus, Ukraine, Central Asia and much of the Caucasus remain part of the empire, but exclude from your analysis peripheral areas like Poland, Finland, the Baltics, and any more extravagant gains they might extract from the Ottomans or others at some point (e.g. Constantinople), as these may or may not remain part of the empire by 2018. Could it exceed half a billion?
Also, what would the demographics look like? Obviously there would be more ethnic Russians, but what percentage of the empire would they comprise? How successful would efforts to assimilate Central Asia be?
It certainly would be the case that in a world where the Nazis had not come to power and invaded much of Europe, including Soviet territory, this world's Russia would have a much higher Jewish population, both in raw numbers and proportionally, though how high it would get would depend on whether Zionism takes off in this world, and how liberal the immigration laws in the United States and elsewhere end up becoming. The Ukrainian population would be much higher as well.
Thoughts?