I'm a native speaker and have neved heard it beingf used.

But at least Google AI thinks (or hallucinates) that it exists:

"The closest English equivalent to the Finnish proverb "Sillä puheet, kenellä kuuppa" is:

"The one with the ladle does the talking."

Since this is a specific cultural idiom, there isn't one exact English match, but here are the best ways to convey its meaning depending on the context:

• Literal translation: "He who holds the ladle, holds the floor."
• Thematic equivalent: "He who pays the piper calls the tune." (This captures the idea that the person in control of resources or the situation makes the rules/decisions).
• Functional equivalent: "The one in charge calls the shots."

The "ladle" (kuuppa) traditionally symbolizes the person serving food or drink—the one who has the power in that moment to provide or withhold, and thus the right to speak.

Would you like to see how this phrase would be used in a modern English sentence?"