Yes, THRIVE is a Scrabble word!

Letter values in Scrabble US: T 1, H 4, R 1, I 1, V 4, E 1.

Is it a valid word?

THRIVE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

grow vigorously
make steady progress; be at the high point in one's career or reach a high point in historical significance or importance

Also: fly high.