In the novel, Snoke seems genuinely afraid of Luke. After BB8 gets back to the Resistance Snoke seems terrified that the New Republic might be making copies of the map so he orders Hux to destroy the entire system that the Resistance base is located in. Hux wants to destroy only the Resistance base planet and claim the other heavily populated planets in the system for the First Order. It would take a couple hours to figure out exactly which planet the base is on, but Snoke is so afraid that the Resistance will make copies of the map to Skywalker in those hours that he orders the whole system destroyed. He doesn't even want to find Luke. He just wants to ensure no one can go and convince Luke to join the fight.
The way Snoke fears Luke and considers him a formidable enemy makes me nearly 100% sure that Luke kicked Snoke's ass at some point.
And part of dark side training involves a lot of pain. So most likely Snoke is going to punish Kylo plenty for his failures, and through that punishment and pain Kylo will grow stronger and complete his training. With that being said, the novel does specifically point out that Snoke takes on a much more affectionate demeanor when he is speaking to Kylo alone and that he treats Kylo different from Hux. Snoke seems to genuinely care about Kylo. Almost like a father and his son. With what Leia said about Han not knowing what Snoke was doing to their son it makes me think Han was an inattentive father, and Snoke treated Ben like a son which is how he was able to manipulate Ben.