Technically yes.
Technically Kasich could win enough delegates still — though it’s unlikely.
There are too many scenarios. Trump has under-performed in lots of races. Cruz has the best chance of taking the nomination or forcing a brokered convention.
It’s politics. Anything can happen.
Yes, Trump can do it, and actually it won’t be all that difficult.
The 8 states thing is NOT about popular vote, it is about delegates. Trump already has 5 such states, and Cruz only 1. The proportioned states are ending soon (March 14, just in time for the big primary day on March 15). Then we’ll be in mostly winner-take-all territory, and Trump will start that off with a bang in Florida (where he’s got a 20-point lead), and get all 99 of its delegates.
He will also likely win NY, PA, NJ, DE and CT (his home state or near it), for 265 more delegates and 5 more states (but he’ll have vaulted over 8 states long before those primaries.
Re: Cruz - no, it WON’T be easier for him. He appeals (in this election cycle) to a much narrower band of people, the very conservative. Not too many of them, percentage-wise, in the vote-rich Northeast, Midwest or Far West (CA, OR and WA). Those are Trump territory, not Cruz territory. Cruz needs to win 4 or 5 states this week, maybe more - that was his plan from the start, and it didn’t pan out because NO ONE counted on Trump being in the race, or being this successful if in it.