I got stuck with a phrase or a word to describe people who are specifically paid to go into a store or restaurants during slow hours to make the business look busy, so that real customers would come in, thinking it's a busy place, and food must be good.
Producers of televised award shows such as the Oscars want any shots of the audience to appear as though every seat is occupied.
When individuals leave the audience to appear on stage (to receive an award, or to present an award, or to perform) their seats could remain empty for several minutes if seat fillers were not employed. This is an actual term which is widely used in television.
I think the word you want is "shill", although I've seldom seen it used except in association with casinos/gambling: https://en.wikipedia.org/wiki/Shill
You already got it! :)
Anything that is done to 'attract' falsely can be called 'paid'. Recently, the topic of 'Paid media' was on the rage in India.
So, one of the options you can opt for is...
We arranged for 'paid customers' to walk into the store. Seeing them, others got attracted; it's a business trick, you know!
These are basically 'fake customers' and should not be confused with 'mystery shoppers'.