how much time needs to pass, from being layoff from a job, could a layoff be treated it as a termination, so that a claim for severance could be filed?

This depends on a few different things including whether there is a layoff provision in your employment contract or offer letter, as well as whether or not your benefits have been continued during the layoff period.

To discuss you specific situation, it would be best to set up a consultation with one of our lawyers who can review relevant documents and get the necessary details from you before advising as to your ability to pursue severance.