Ofcourse they know about BTC, as it is one of the best assets for investing in, and I believe that most billionaires, like Bill Gates, own quite a bit of them, who know about it and has knowledge that the technology can be revolutionizing in the currency world. Bill Gates even declared that he understood the potential of bitcoin to be more than fiat, and since that time, many other billionaires, and CEOs of various companies and even people like John Mcafee have declared their trust on bitcoin.
This definitely shows that they not only know about bitcoin and are very much aware and educated about it, they also take a keen interest into the technology.