It would be tough to prove any direct role, but I feel she did contribute to the further alienation between Nicholas II and the people of Russia. During World War I she was referred to as "German," which is true, she did come from a German family (and granddaughter of Queen Victoria). She let Rasputin hang around when most others saw him as a debauched charlatan. To illustrate how alienating she was, Nicholas II's own cousin, along with other very high ranking nobles, were among those who eventually killed Rasputin. She also tried to convince Nicholas II to come down hard on liberals looking for more civil representation, even calling for their exile to Siberia. But it seems Nicholas II really didn't need all that much convincing, he honestly felt it was his sacred duty to lead Russia. So yeah, she did things that had a negative influence, but it would be hard to draw any direct causal contributions to the turmoil of 1917, especially taking into consideration the actions and inaction of Nicholas II, who as tsar had a much more direct role in events.