Your link to The Gulag Archipelago as an expository on Marxist doctrine also reveals a complete ignorance of what Marxism even is, on a very basic level. The Gulag system was a pure product of Stalinism, which was an implementation of communism that directly rejected Marxist doctrine. Explicitly and directly. Communism is not stalinism is not bolshevisim is not marxism.
The turn to marxist criticism in humanities academia really has nothing to do with anyone wanting to lead a revolution or thinking they will overthrow capitalism or whatever. It is a reaction to lived experience that expresses itself in a particular mode of analysis.
"In the world around me, the economy is imploding and everyone is anxious and on edge and complaining about inequality. I think I'll interpret this novel through the lens of Marxist cultural criticism as a reflection of how I experience the world right now" is all that is going on.