Likes and dislikes are engagement signals. They indicate that a viewer cared enough to react.
However, they are not a direct ranking switch. A video does not go viral simply because it receives a high number of likes. Likewise, a few dislikes will not destroy performance.
YouTube evaluates satisfaction more broadly. Watch time, retention, and continued viewing carry more weight.
Likes and dislikes contribute to the picture, but they are only part of it.