How does the corona-virus survive,? I heard or read it's not biologically alive.?

That is correct. Viruses are not technically alive. They are complex molecules that can cause the body of a particular host species to generate duplicates of the viral molecule.

viruses survive by invading cells and taking over the functions of the cell to make more viruses

No viruses are biologically alive by scientific definition of alive. They're like active or inactive strands of RNA (not DNA) but if they get into a host with cells (viruses have no cells), then they can reproduce. Viruses depend on living animals to subsist but can't live on their own.

It is active only when inside a living host - outside, it degrades after a few days - but it spreads from host to host in crowded situations like bat caves.

probably cause its spreading everywhere