Job Loser/On Layoff includes only those who are on temporary layoff, which means they expect to be recalled back to work either at a specific date or within six months (see the Unemployment Concepts section of the CPS Interviewer Manual). Those who are permanently laid off will generally be included in one of two places:
Those who are searching for work will be counted as unemployed and have WHYUNEMP = Job Loser/Other
Those who are not searching will be counted as out of the labor force, and will be NIU for WHYUNEMP
I don’t believe there is a reliable way to identify all of those who are permanently laid off and currently NILF in the microdata, versus those who were fired. You may be able to get at this partly using the unharmonized variable UH_WHYLFT_B2. You can find additional detail on layoffs in the Displaced Worker supplement, but this is only fielded once every two years.