It's got to be difficult for the Cruz campaign, hearing everyone say that South Carolina was a "loss" for them, when they finished about exactly 1,000 votes (out of several hundred thousand cast) behind Rubio. However, the characterization is fair, because of the comparative expectations placed on the campaigns based on the state of the electoral terrain.
Cruz's entire path to the nomination - and his pitch to voters and donors - centered around his strength in the heavily evangelical South. Cruz was supposed to have a very good Super Tuesday, due to the heavy concentration of Southern states, and position himself as the only remaining (and viable) challenger to Trump. For Cruz to lose to Trump by 10 points in South Carolina was bad; for him to finish behind Marco Rubio (even by a very small margin) was worse.
Rubio's path to the nomination now centers around his ability to deliver a quick knockout punch to the rest of the field, including Cruz. His pitch to voters and donors centers as the true anti-Trump candidate centers around his ability to run as strong as Cruz in the South, but better everywhere else. He's also leaning heavily on the narrative that support is coalescing around him, and that time is of the essence.
He's made a clear statement with respect to the first portion of that pitch by beating Cruz on his "home turf." Now the election shifts to Rubio's "home turf," in the state of Nevada. Not only is the state at least theoretically more ideologically suited to Rubio, Rubio has strong connections to the State of Nevada as well.
Rubio has survived one disappointing finish in this election cycle. I do not think he can survive another. In order for him to continue his momentum, he needs to win clearly and unequivocally against Ted Cruz in tomorrow's Nevada caucuses, and it would not hurt to come surprisingly close to Trump in the process. Anything less and this continues to look like a deadlocked race for second place, and Rubio begins to look like a paper tiger.
Cruz failed to live up to expectations on Saturday, and it will likely hurt him. Rubio is now the candidate facing expectations in Nevada; we will see if he is able to fare better.