It is the first time since 2010 that Arsenal have reached the final eight and Arteta said: "So happy. It has been 14 years, which is a long time for a club like Arsenal and it shows how difficult it was. We really had to dig in to find the magic moment at the end. We're starting to create an unbelievable energy in the stadium, we were all pushing to get it done and together we have done it.
"You're very nervous (watching a penalty shootout), hoping for the best but you know it's a bit of a lottery. We had prepared the day before so credit to the goalkeeping coaches and everyone that has contributed. It's really difficult to play against Porto, they are really competitive. We didn't get many moments where we could control the game, they're a really good side.
"We scored a goal in a really important moment, we tried to create chances and in the end we managed to do it. There's a lot at stake and every detail is important, you're defending your team on every decision and it's part of the game."
On being in the Champions League quarter-finals, he said: "Unbelievable, that's where we want to be. We've been patient, worked so hard and a lot of people have made good decisions and showed courage in difficult moments and this is where you want to be."
Arteta also was asked about the fans on the night: "Thank you so much. We absolutely love them, the energy they gave, how positive they were, how they contributed. They made us win, it's as simple as that."