Is it possible to build pivotviewer collection of data from database using ria services & EF ?
Essentially yes. The major part of creating pivot collections however is the creation of the deepzoom images and collections. If you truly need to build dynamic collections, then start off by looking at the JIT server example.
The approach I have personally (successfully) taken with dynamic collections is to run a batch process which runs every x minutes (for example) and re-creates the pivot collection using pauthor.