The estimated life span of a DVD is around 25 to 200 years and depends on environmental factors and how often one uses the DVD.
The Smithsonian Institution's 'Guide for Librarians and Archivists' states that under recommended storage conditions, DVD-R and DVD+R discs might have a life expectancy of 100 to 200 years or more. Moreover, the lifetime for the DVD-RW, DVD+RW, and DVD-RAM discs is up to or more than 25 years.
The Austin Public Library states that the optical discs such as CDs and DVDs have lifespans of up to 100 years. It also mentioned that the fluctuations in temperature and humidity play a role in a DVD's lifespan.