Look at the statistics. Russia's a strong country. In addition China will not support Russian. Why is it necessary? China's economy is very dependent on America, and in the case of defeat and the disintegration of Russia, China will take Siberia.
Russia is the nation having the largest number of nuclear weapons. In addition to that, they have the most powerful inter-continental ballistic missile in their possession. Only retards will go for a war against Russia.
No Russian nuclear weapons will not help. If the war is in Syria, then Russian will not be a reason for the use of nuclear weapons. Besides the Russians do not want to retaliate.