Montesquieu, Wittfogel, and Sachs are the old ones. Modern writers acknowledge geography isn't destiny, but it would definitely be fighting uphill for Russia to maintain democracy. Mobile middle class seems to be the real driver of democracy, and coastal trade is what created that in most modern democracies. Seems like maybe technology could change that. But big regions make mobility harder. If you have to move half a world away to reach different laws the pressure to retain you is less. Where a doctor in Hungary can pack up and take a train to find a government more to their liking. The shrinking of the middle class drives authoritarianism fairly reliably according to these sources. Sometimes the older ones call it the merchant class.