The early effect of Gallas' leadership skills were initially hailed as The Gunners enjoyed a blistering start to the 2007/08 campaign.
"I think it has been difficult for him. I have been talking to him and he has been hurt by the criticism he has received," former Gunner Vieira said at an event run by Ford's Feel Football debate website www.feelfootball.com.
"Of course, he had a difficult moment. He is a really strong player who is committed to the club. He wants to prove that he deserves to be Arsenal captain, I know he wants to be a successful captain at Arsenal, and he will do everything he can.
"He is a really emotional person sometimes. He expresses his feelings and that is why he is so popular on the French national team.
"I hope he stays as captain. I think he is a leader of the team. He has experience. I think he has the full support of the players.
"It would have a bad effect on him (if he lost the captaincy) and everybody else in the team as well. If you had the captaincy taken off you after a year it would be difficult psychologically to start the next season not as captain.
"He might think about what he did wrong and think that he lost the manager and the players' trust. It would be a big blow for him and for the club and players."