Its just like when McAfee is busy shilling coins in Twitter. Many people are becoming interested in the coin he shills thus they will invest into it hoping that they will gain profit.
Same as when Ver is on a new project back in the years. Whenever you see Ver in the team especially when it is a new project, there is a high chance that the token sale of it will be a successful one.

Musk is a public figure and he is being followed by so many people thus tweeting DOGE is already a big factor of its increase right now. You also saw what happened to Bitcoin when Tesla bought Bitcoin right . No need to get confused. He is just using his fame, power to pump DOGE and other crypto coins. That's it.