The fact that many of Lenin's collaborators in the Bolshevik Party, and in the Russian and European revolutionary movement generally, were of Jewish origin is indisputable. It's worth noting as a historical anomaly with readily identifiable causes. It is not anti-Semitic to point this out, unless one veers into Nazi ravings about "Judeo-Bolshevism". I doubt very much that this is Solzhenitsyn's thesis.
Now Stalin - there was a real anti-Semite.
I agree. The evil parties in old Russia were leftists, some who were formerly Jews. We have the same problem in modern America, where the evil parties are leftists (aka liberals), some who were formerly Jews.
I read somewhere that he was married to a Jew.