The main reason why a coin increase is because of demand due to it's use case. But what Elon musk is doing with Doge is caused shilling. He is shilling the coin and it won't last long. Doge could actually increase well without Elon musk tweeting it.
There is no use case of dogecoin unless elon musk start accepting it for the tesla.
The reason for the dogecoin pump is only elon musk. If he stop shilling this coin, we may see this coin die within no time.