Translation:Yes, we are going to eat at Genki Sushi.
This Hawaiian parts of speech link may help you. Look at (slide 5).
NĀ ʻANA: (REVIEW) NĀ MĀKA PAINU
= The tense markers
Parts of speech (Grammar Link): https://www.slideshare.net/malama777/na-maka-painu-1
The prompt is a bit ambiguous. When you read that prompt it should indicate to you first of all that it is an action in the future. We are going to eat = We will eat. That would mean you need to say E ‘ai ana kākou ma Genki Sushi.
However, you could also read that as you are literally going to Genki Sushi to eat, which implies movement instead of a future action. That would read like this - ʻAe, hele aku kākou e ‘ai ma Genki Sushi.
I would say We are going to Genki Sushi to eat to avoid ambiguity. However, you do have a valid point to ask that question for clarification.