And Lewis maintains getting Gatland to extend his spell would be a real coup for Welsh rugby.
He said: "Everyone knows I am a big admirer of Warren and I was so thrilled and pleased that I was able to secure him for Wales back in 2007.
"I think he has done an outstanding job for us. The rugby we are playing is so exciting and so engaging.
"I think Warren Gatland is right for Wales. I have always believed that and I would like to have a relationship with him that carries on for many years to come, beyond the World Cup.
"That is my personal view, but that has to be discussed with the board of the Welsh Rugby Union.
"This sort of decision needs to be based on all the issues. It's not a black or white, yes or no decision.
"This is a very complex decision based not only on the way we are developing professionally, but all of the personal circumstances involved as well.
"The commitment Warren has given Wales so far, bearing in mind he has two children in New Zealand, has been absolutely extraordinary.
"To get it sorted ahead of the World Cup is very, very important.
"If you don't, it creates an unnecessary pressure and a distraction and all of a sudden we get back into a position where someone is saying they will be measured solely on one knockout competition."