To what extent, if at all, did Russia have a Marxist revolution in 1917?
There was a great deal of Marxist influence in the 1917 revolutions in Russia, both in the March overthrow of the Imperial government and the seizure of power by the Bolsheviks in October. The initial revolution was the result of food riots, combined with a naval mutiny, the creation of "Soldier's and Worker's Soviets" and action by politicians in the Duma. The soviets, or collective groups, were largely influenced by Marxist ideals. The most important Marxist group at the beginning was the Social Revolutionaries, split into Left and Right SRs, although there were others as well as non-Marxist groups, including democrats, anarchists, and nihilists.
Philosophically, the most important Marxist was Leon Trotsky, who adjusted the Marxist concept with his idea of skipping the interim steps of Marxist social theory and entering a state of permanent revolution toward a socialist/proletarian state. Trotsky was also in charge of the Red Army during the Civil War following the Revolution.
Of course, in the end the most important Marxist involved was Vladimir Ulyanov, known as Lenin. He engineered the Bolshevik coup which took power late in the year, and dominated the leadership of the Revolution from that point on. Where Marx and Engels developed their theories in a fairly academic environment, Lenin spent his life planning and acting out revolution in the real world. He put down the challenges to the Bolsheviks of the Social Revolutionaries, democrats and other political opponents by his reasoned arguments, force of personality and personal leadership, and the fact that beneath all that he was simply both more clear-sighted and ruthless than his opponents.