Hey Mohan,
So that blog post you linked to is about Red Hat's commercial product offering based on the upstream Debezium community project. This is centered around Red Hat's distribution of Apache Kafka and Kafka Connect. I.e. you could use Flink to read data from those Kafka topics, with such pipeline having "at-least-once" semantics.
The Ververica CDC connectors for Apache Flink (which I suppose is what you're referring to) are a separate development of Ververica, using the Debezium connectors under the hood. I don't know about the exact delivery semantics of that, i.e. you'd have to ask in their community about that.
If you want to learn more about Red Hat's offering around Debezium and its support aspects, can you please shoot me an e-mail with some details to gmorling AT redhat DOT com ?
Thanks,
--Gunnar