Does being cryonically preserved prevent an afterlife?
No.
Cryonics FAQs
Cryonics - Frequently Asked Questions About Cryonics
Why wait till people are dead to cryopreserve them?
Regulatory agencies and ethical considerations require that an individual be pronounced legally, although not biologically “dead” before cryonics protocols take place. This does not mean that the brain or even the “soul” is irretrievably damaged, as evidenced by hundreds of medically documented cases.
What is cryonics?
Cryonics is a process of reducing biological damage to enable a bridge to a future advanced medical technology.