According to Ethnologue, there are more than 100 million Russian speakers outside of Russia. It is the primary language in Belarus and half of the Ukraine (and is known by most people in the country). Almost 7 million people in Poland know how to speak it.[1]
English is probably becoming more of the lingua franca of Eastern Europe, but still, if any Slavic language were to serve as the lingua franca, it would be Russian. It's the Slavic language with the largest international presence, and in contrast to constructed languages, it actually has a large speaker base and significant cultural heritage.
