Since there are many references that a RF uses a slightly different approach on splitting a node in comparison to Vanilla Bagging. Does Gini index play an active role in the split or it's just another index like Information Gain to measure the improvement of the uncertainty from one node to a next?
Definitely yes, it is one of the many criteria you can set in the tuning to determine a split in the node. Of course it depends on the type of problem you face. If you need this is a good explanation of RF