On Dragon Ball Super Episode 18 , Whis made an analogy about Goku and Vegeta's power level to Beerus by comparing it to Beerus' castle. Goku and Vegeta were barely even able to sense the ki of Gods at that point.
On Dragon Ball Super Episode 21 , Goku admitted him and Vegeta couldn't beat Beerus even if the fought together, and that Beerus ki was WAY bigger than theirs.
On Dragon Ball Super Episode 22 , Beerus said he needed Goku and Vegeta to become stronger fast, otherwise they wouldn't even make good playmates for him, implying he was toying with SSG Goku the entire time.
In the Apr 2016's interview of Akira Toriyama and Toyataro, Toriyama stated he had no plans for Goku or Vegeta to surpass Beerus and Whis.
Toyotarō: … I get the feeling I’ve just heard something amazing (laughs). Lord Beerus and Whis turn up in Dragon Ball Super, and have become an unsurpassable wall for Goku and the gang. What do the two of them mean to you?
Toriyama: Well… First off, right now I don’t have any plans for Goku and Vegeta to surpass Beerus and Whis.