Yes, arrows work on knights. At Agincourt the English did not decimate the French with crossbows but longbows. Japan had those too.

Without trying to be dismissive this question isn't really answerable because it's based on a false premise. That you can compare Knights and Samurai. Knights and Samurais are not npcs with stats in a rpg. They were not a monolith. They were professional warriors who knew how to adapt to how war was fought. Yes the French knights were decimated by longbows... that's why the next time they showed up with a lot of crossbowmen (they still lost but they tried to adapt). When the gun was introduced to Japan the warriors immediately adopted it, just like the knight did in Europe. You can't compare them because faced with a new situation, they will change and adapt. They don't follow a script.

There is no one knight you can compare to one samurai. There was a wide range of different techniques to use in different situations. Due to Hollywood we tend to forget that this, for example did you know that European knights often used axes? In close quarter is easier to use than a sword. We rarely see that.

In the end those are two warriors who can adapt, they are two professional men who fight broadly with the same technology... so depending on the situation it's basically 1 vs 1. Because it's one man without firearm and with a full armor against one man without firearm and with a full armor.