When it comes to companies over 100 years old, private ownership beats publicly-held two-to-one: Two-thirds of the companies are private, often family-owned companies passed from generation to generation. Though this seems like a significant statistic, in fact the majority of all U.S. companies are privately-owned - far more than two-thirds - so it's hard to draw any conclusions regarding private vs. public ownership relative to survival.
This doesn't seem to change the opinion of the old private companies we have interviewed, however: when asked what they believe have been the most important factors in their survival, they almost universally indicate that staying private was key. They see this as a matter of being able to maintain control of their policies and practices with company values and purpose in mind rather than having to respond to the short-term demands of the financial market. An interesting question to pursue with those old companies that are publicly-owned is how successive management teams have been able to keep their decisions driven by company values and purpose without being unduly influenced by reaction of the stock market and financial investors to short-term financial performance.