The Swede scored twice in Saturday's 3-0 win against Sunderland.
Arteta told Sky Sports: "Confidence is the magic word. When you feel confident, when you feel important, when you feel at your best, that's when you can really take your game to the highest level. We're really behind him at every moment to try to help him, try to support him. And he's delivering, and he's in a really good period now.
"Of course, when you put on that shirt there is a lot of responsibility and high expectations, and you have to live with that. During your journey you will have moments where things are going really well, and then others where it will be tough.
"With Viktor it is very difficult to understand his emotions because he looks you straight in the eye. But he doesn't seem to be affected very much by real peaks or troughs. He is very demanding of himself: he is constantly trying to improve."
Arteta continued: "I love his character, how he approaches every day and the fact that he is so focused on the present, what he has to do, and that he has a genuine desire to help the team in whatever role he has."
Gyökeres has scored a total of 13 goals and two assists in 32 Arsenal matches this season.