Question

how can Bolshevik give autonomy to non russian nationalist if they were not part of russia?​

Answer 1

Answer:

The main reason that the Bolsheviks were able to seize power was because of the Provisional Government and their weaknesses, and other factors that led to them taking power in October 1917. ... The Provisional Government also lost support of the national minorities by refusing to give them a degree of autonomy.

How did the Bolsheviks secure their power during the civil war?

In short, the Bolsheviks were able to win the Russian Civil War because the Whites failed to secure the support of the different national groups, key foreign powers, and the peasantry, while Bolsheviks enjoyed much more authority within Russia and were therefore able to assert their power over the Whites.