Trump has led the polling in every state voting today  except three (Texas, Arkansas, and Minnesota), and he is very likely to win at least seven of the eight states where he has led. While the delegate allocation in these states is proportional, there are fairly high thresholds in several states (Alabama, Georgia, Tennessee, Texas) that require a candidate to get 20% to be awarded any delegates. Some other states have thresholds of 10 or 15%. In both kinds of states, either Cruz or Rubio has been falling short of these thresholds and may receive nothing.
Texas should be a particularly interesting election, because there are so many delegates at stake (155) that could end up being divided up three ways. Cruz has been consistently leading in Texas, but he is averaging less than 40%. That leaves him short of the 50% winner-take-all  trigger, and that should allow Trump to pick up a significant number of delegates. If Rubio remains at 18% in Texas, he will miss out on delegates entirely.
Minnesota  is Rubio’s only realistic opportunity for a win. The last poll was taken there over a month ago, and Rubio’s lead was very small and may have disappeared in the meantime. He enjoys the backing of state party leaders and may be able to eke out a win in a low-turnout contest, but it will scarcely make up for being blown out by 10 or 20 points everywhere else. Rubio will receive more delegates from second or third-place finishes in other parts of the country, but finally coming in first somewhere would at least allow his campaign to say that they don’t always lose. Needless to say, if a candidate can’t win more than one race through Super Tuesday he certainly isn’t going to be the nominee.
Trump and Cruz were neck-and-neck in Alaska  two months ago, and Cruz was slightly ahead the last time anyone checked in Arkansas at the start of February. In every other state today, Trump is set to win, and in almost all of them he should win easily. He leads by 10 points or more everywhere from Oklahoma to Vermont to Alabama to Georgia to Virginia. The election in Massachusetts will also be a walkover for Trump. If Cruz comes up short in Alaska and Arkansas, we could be looking at Trump victories in nine states tonight.
Cruz has been losing some ground in Southern states ahead of today’s voting, and that puts him at risk of finishing third in Alabama, Georgia, and Virginia. He has just enough support that he should qualify for delegates in Alabama and Georgia, but coming in behind Rubio in Southern states where Cruz expected to be very competitive will be a bad result for him. The continued presence of Carson in the race can’t be helping him, since Carson continues to pull 6-10% in many states that might have otherwise gone to Cruz. If Cruz can win somewhere outside Texas, it will be in Arkansas, and notching a third win there would help boost his claim that he is the Trump’s strongest competition. If Cruz is limited to just one win today, it will still give him minimal bragging rights that he can beat Trump in his home state, and that is more than Rubio will be able to claim in two weeks.
Barring some surprise collapse in turnout of his voters, Trump is about to romp all over the country, and seems very likely to do so over the next two weeks as well.