this has nothing to do with them creating their own cryptocurrency though.
and the rise may not be not as much as you may think. of course it is kind of obvious that if the big companies start accepting bitcoin, the adoption will grow and the news alone will cause a big rise. but it won't be that big because if you look around there are currently big companies like Microsoft that do accept bitcoin payments. maybe not in the most obvious way but they do it. and price never "skyrocketed" because of it!
Being pioneer, acceptance of cryptocurrencies in general has an impact on Bitcoin. Think about what happened last month, People talked about Bitcoin, Bitcoin is advertised and is even in the news, People start taking Bitcoin seriously and people started to invest in cryptocurrencies and Bitcoin. Bitcoin reached around $20,000 in value. If companies, lets say Alibaba or Amazon or e-bay would prefer cryptocurrency or just use bitcoin as an acceptable currency in buying products thru them, I do believe that the price will climb again. Microsoft accepting bitcoin still has an impact, it may not have skyrocketed because of it but somehow Bitcoin gained support. Currently we did experience a dip or correction in prices as they say it and as I've said not only Bitcoin is affected but the other cryptocurrencies as well. Again on Facebok or Google creating its own brand of cryptocurrency, this will be a hit since both has a wide range of market already and have established name for themselves but if they start accepting bitcoin or satoshi's as payment for PPC or Boosing advertisement. Prices will definitely be affected on the positive note. Peace out!