Beto only got close because Cruz made an ass of himself. Beto will learn that the hard way when he decides to run against Cornyn.
Beto is also going to learn, the hard way, that 40% of real Hispanics in Texas vote Republican (except when that Republican makes an ass of himself).
Cruz also ran a terrible low-energy campaign with many, many missteps. He got started late, continued to piss off his supporters in the early parts (he made them pay for campaign signs in an evident attempt to make a profit) and basically didn’t fix these and other problems (”I’m Ted Cruz! You should vote for me! Thanks!” being his entire message for a while) until October. Trump had to come bail his arse out.
And Beto was swimming in money from liberals in other States.