The Titans are favored by 1.5 in Houston, and based the first three weeks of this season there's not much reason to think the Titans can't easily take this game by at least a field goal.
For one, we haven't seen much from the Texans to find them impressive at all. Sure, Deshaun Watson has been fun and surprisingly competent for a rookie in the opportunities he's gotten, but their offense as a whole is still thoroughly underwhelming. Their defense, presumably their better unit based on roster talent, surrendered a total of 65 points in the two games where the opponents' offense was not coordinated by the since-fired Ken Zampese.
The Titans, on the other hand, have a stellar offense ranked #2 in DVOA per Football Outsiders. In week 2 they blew out a Jacksonville team 37-16 that had absolutely embarrassed the Texans 29-7 the week before. Their defense hasn't been great, but with their offense putting up points it should be plenty to keep the Texans from building any sort of lead. They're also ranked #7 in special teams DVOA to Houston's #21, so the kicking game should favor the Titans.
I don't expect this to be particularly close. The Titans could be giving 5.5 and I'd still be very comfortable with this pick.