The 3-0 win sees Arsenal reach the last 16 3-1 on aggregate.
Emery said: "His development is like we want, he has big ambition and big quality and sometimes we need more quality with him and sometimes we need to be stronger in midfield with different matches, it depends. His development with us is very important and he is playing with consistency and I think he is improving. His quality of his football is very important for us and for me."
He added: "We can and maybe if we can say 16 teams, one is Arsenal, but it is very difficult and a lot of teams want the same. We need to create a big atmosphere in this competition with our supporters and this feeling can give us more opportunities after our quality and capacity as a team. We need to feel stronger in this competition with every supporter and create this atmosphere around us."