Gatland led the Lions to victory in Australia last summer, the first time the tourists have won a series for 16 years.
And with a World Cup coming up next year, Lewsey is excited about what Wales can bring to the table under the Kiwi's leadership.
"Arguably, he is one of the most successful coaches in the world and he's got a proven track record of delivering when it matters most," said Lewsey.
"That mental edge, of knowing how to win and doing the right thing at the right time.
"You've got to back our guys as we've got, arguably, the best coach in the world in charge."