The highest serious estimate i've seen for the Russian population in 1800 was about 40 million, and I can't see how it could have been any higher. I'd say Russias population was probebly around 36-37 million, compared to say, 25 million for France. Do remember that Russias population skyrocketed during the 19th century (as did most of Europes), while Frances was relativly stagnant.