According to this commentary on the Bhagavata Purana by Swami Prabhupada:
By controlling the breath, the perfect yogī can continue his life for as long as he likes. Sometimes we hear from the Vedic literature that some personalities from the Vedic age, such as Vyāsadeva and Aśvatthāmā, are still living. Here we understand that Maru is also still living. We are sometimes surprised that a mortal body can live for such a long time. The explanation of this longevity is given here by the word yoga-siddha. If one becomes perfect in the practice of yoga, he can live as long as he likes. The demonstration of some trifling yoga-siddha does not constitute perfection. Here is a factual example of perfection: a yoga-siddha can live as long as he likes.
Questions:
Are those two people (Vyasa and Ashwatthama) still alive?
Has anyone used yoga to live for supernatural lengths of time?
(Note: Question has been edited based on this recommendation on meta)