The club-record signing impressed in a cameo appearance as a substitute in their Premier League opener at Newcastle last week.
There are now calls for the attacker to be handed his first start as Burnley head to the Emirates on Saturday – although Emery is holding off on making his call.
He admits Pepe is still adjusting to their style of play after his switch from Lille late in the transfer window, whilst his pre-season started late after being in African Cup of Nations action for the Ivory Coast.
Speaking at his press conference on Thursday, Emery said: “I am going to decide tomorrow because now is a small difference for my decision about the player.
“It depends how they will be tomorrow in the training. Pepe is training with us, improving with us, knowing us.
“He’s understanding our style little by little and physically getting better. He is more close to help us at the beginning [of the match].
“Each player is different. After Newcastle and this week the players are working well. We can decide to choose different options in each position. Really I think we need to be competitive.
“We need different options to decide who is better each match. The new players, the players who were with us last year, the young players, we can achieve our way each match with confidence.”
Emery also confirmed Mesut Ozil and Sead Kolasinac will once again be available for selection and insisted they are “100% ready” to return.
The pair missed the trip to Newcastle due to security concerns but will now be available to feature at the weekend.
“They are 100% ready to play,” insisted the Gunners boss. “Their mentality is 100% focused on us.
“They have their minds here. I want to help them with normality with us, with the focus on training and each match. Of course I am pleased they are back. First as a person, after as a player.
“They came back training with us on Tuesday. We had off but they came to train with us. Mesut was a bit sick so he didn’t train yesterday but he trained today.
“Each day gives us more information whether they will play Saturday. We will wait till tomorrow to decide if they play.
“When they are training and consistent every day, we can choose them and that is good for us.”