Yes he is, Where do you get 66 billion $. Investor support dosen't mean he has the financing. Don't quote a tweet, get some real sources.
"And yet it also left many questions unanswered, namely how Musk -- who owns almost 20 percent of the company -- would be able to come up with the $66 billion necessary to complete the transaction. At $420 a share, Tesla would have an enterprise value of about $82 billion including debt. To take it private, the billionaire would have to pull off the largest leveraged buyout in history, surpassing Texas electric utility TXU’s in 2007."