Farrell also came under pressure after England's Championship defeat to Wales in mid-March but Gatland doesn't expect those high-profile loses to have any effect on his confidence come the tour opener against the Barbarians on June 1.
"It's been tough for Owen but he has shown in the past that he is one of those players who responds really well to any adversity or criticism and comes back better and stronger," said Gatland.
"That's one of the reasons why we like him so much. He is mentally tough and he has a strong character. We're sure he'll react really well to any criticism from outside and I'm confident he will do well on tour.
"And, although he wouldn't have wanted it and while it is disappointing for Saracens, it is a bonus for us to have him available for training. The Saracens result gives us an opportunity to work with him in the next couple of weeks prior to the first game."
Farrell appears the favourite for a fly-half start when the tour kicks off against the Baa-Baas in Hong Kong as Irish rival Jonathan Sexton will have been involved in the RaboDirect PRO12 Final seven days earlier.
Sexton won't be available for the Lions' training camps in Wales this week and Ireland the week after as Leinster go in search of a domestic and European double.
The 27-year-old playmaker will join fellow Lions Cian Healy, Jamie Heaslip, Rob Kearney, Sean O'Brien and Brian O'Driscoll in attempting to win the Amlin Challenge Cup against Stade Francais at the RDS on Friday night before facing Ulster in the PRO12 showdown at the same venue on May 25.