Which translates to: How did Dad overcome all of those hardships?
The key word is “norikoeru” （乗り越える）which means to overcome/to surpass - and in most contexts, it’s used to describe overcoming hardships/obstacles. Note the key particle is “Ga”.
A sentence in Japanese doesn’t always need a subject - so when Boruto uses the particle “ga” combined with the word “norikoeru”, it indicates something one-sidedly related to Naruto - ie. How did Naruto, overcome all his hardships?
Had Boruto said “Touchan wo douyatte norikoetekitano” , with the key particle as “wo”, that may have indicated that he was asking Sasuke “How did you surpass my father?” , but the issue here is, the word “norikoeru” isn’t really used to overcome other people/things. It’s sole use is pretty much to describe overcoming hardships/obstacles on the path of life - so it would be weird in Japanese to ask how X surpassed Y using the verb “norikoeru” in the first place.
If Boruto wanted to ask how Sasuke got stronger then Naruto, he would say something like:
どうやって父ちゃんより強くなったの (Douyatte touchan yori tsuyoku natta no) How did you get more powerful than my father
父ちゃんをどうやって倒したの (Touchan wo douyatte taoshita no) How did you defeat my father
Or something along those lines.
I am writing this because I think this trailer suggests that Boruto is finally coming to understand his father more, and what Naruto had to go through as a child - leading to Boruto’s own character development and maturation - rather than going off on a power level spiel, which is far less interesting to me.
On that note, this movie looks like it’s gonna be pretty good.