Bill Gates stated that the Bitcoin is the future and that it is better than currency. Would you assume that his statement (as one of the many reasons) added value on Bitcoin which made it stronger and more stable in the system? 
Bill Gates is one of the most important people on this planet and I think that his statement somehow affect the price of bitcoin. We can not see them yet but I do believe that there is a small movement in the price of bitcoin after his statement. It can not make bitcoin more stable but more valuable 