Is there any documentation/video/articles which help us determine below:
1) For a new site, How many publish instances are needed?
2) How many dispatchers would be sufficient?
@arvind There is no fixed architecture for this, it usually depends on many factors.
However, there would be a minimum of 1 Author Instance, 1 Publish instance, 1 Dispatcher, and 1 Load Balancer. And on production- Usually, there are multiple publish instances and dispatchers to allow for redundancy, increased performance, and increased traffic to the site.
It depends on the number of visitors you are expecting on your site. There is no fixed architecture it all depends on your requirements. It should have minimum of 1 author, 1 publisher, 1 dispatcher and 1 load balancer. Number of publishers should be same as dispatcher as there should be 1:1 mapping.
AEMaaCS is scalable dynamic architecture with a variable number of AEM images.
Please find below a link which elaborates how it works and impact live environment.