CRDTs is an acronym for Conflict-Free Replicated Data Types. They are a way of structuring data such that you no longer require a centralized data store or centralized source of truth.
Are CRDTs related to Blockchain?
When I try to explain CRDTs to people, I end up discussing how part of the power of them are in how they enable decentralized data that is eventually consistent. This, I think, makes people think of Cryptocurrencies and Blockchain because that is the other big tech idea in their minds that is correlated with decentralisation.
A Blockchain is a distributed ledger. CRDTs facilitate a distributed data store. A ledger is a type of data store, similar to a write-ahead log