Lol, Cruz ain't winnin' by eighteen points.
Um Greg Abbot will be on the ballot so it’s unlikely but there is a 30% chance he wins by 18 or more.
It's still highly unlikely Cruz will win by that much and a 30% chance is too high considering that Cruz himself is underwater if I'm not mistaken.
Ted Cruz has a good approval rating.
Admittedly this is not the most current poll but from October he has a 38-43 approval rating which is not great.
https://texaspolitics.utexas.edu/set/ted-cruz-job-approval-october-2017