Can the metrics be affected if the tracking site faces outage? Does they get reset ? and How much data or metric loss happens?
Are you talking about Matomo outages or outage of the tracked site?
In the former case, normally all data during the outage is not collected (but you may be able to replay it if you still have the access logs). If your website if offline, there is nothing to track during the time.
My question is - if my website goes offline and get up after some time then does Matomo(piwik) reset value of metrics for my website and start from new or it continue with as it is from previous.
Matomo never resets or deletes tracked data. From Matomos view it will seem as if for the downtime nobody visited the website. (Which technically is what happens)
Thank you for your inputs.