Srila Prabhupada writes in Bhagavad-gita As It Is that, “The process of speaking in spiritual circles is to say something upheld by authority. One should at once quote from scriptural authority to back up what he is saying.” The scriptures have authority, and so too does the acharya. Therefore what we say gains strength when we can quote scripture or legitimately uphold our statements with the words “Prabhupada said.”
By the mercy of the spiritual master one receives the benediction of Krishna. Without the grace of the spiritual master, one cannot make any advancement.
Srila Prabhupada in his commentary to Srimad Bhagavatam 4.28.47 says, "The disciple and spiritual master are never separated, because the spiritual master always keeps company with the disciple as long as the disciple follows strictly the instructions of the spiritual master. This is called the association of vani (words). Physical presence is called vapuh. As long as the spiritual master is physically present, the disciple should serve the physical body of the spiritual master, and when the spiritual master is no longer physically existing, the disciple should serve the instructions of the spiritual master."
Now, where are those instructions? Those instructions are enshrined primarily within his books and teachings. As Srila Prabhupada stated upon his return to Vrindavana from London, shortly before his physical departure, “I will always be with you through my books and my orders. I will always remain with you in that way.”
So we understand that Srila Prabhupada lives forever by his divine instructions and the follower lives with him.