He admitted five charges and was given four and a half months' home detention and ordered to repay $4781.
The court also heard about more recent, unrelated offending.
In August, Grewal was sentenced to a year's supervision and 400 hours' community work at Hamilton District Court on counts of assault, wilful damage, threatening behaviour and resisting police.
Judge Anne Kiernan told the pair the exploitation they carried out was "significant".
"It was essentially a money-go-round scam that took place over a long period, really set up to dupe the authorities, appearing to comply with the statutory requirements," she said.
"Not only was this immigration fraud but the victims of these offences are in fact your compatriots - the same ethnicity as yourselves."
One victim said he had spent thousands of dollars on a string of failed visa applications, while another spoke of the "empty promises" made by his bosses.
"Working at Masala restaurant made my life hell," he said.
Gagandeep Singh worked as a waiter at the Bucklands Beach and Mission Bay premises for nearly a year while in New Zealand unlawfully.
He worked up to 11 hours a day, sometimes seven days a week, and was paid $250 after a week of unpaid "training".
Jain gave Mr Singh a letter offering him the position of assistant manager, working 30-40 hours at $15 an hour, to help him attain a visa when in reality there was "no intention" that would be the case.
He eventually left in 2013 after having effectively been paid $2.64 an hour during his tenure.
In September 2014, Fijian national Bimal Roy Prasad answered a newspaper advert for a chef.
After working for more than nine weeks, he was paid $40.
In more than one case, workers were told to submit timesheets indicating they were working about 30 hours a week, when in reality it was usually more than double that.
A waitress known only as Robin worked for $3 an hour at the Takapuna restaurant for three months before she was told she was being transferred to Mission Bay.
When she queried the decision with Jain, she was told to clean her boss' Remuera house.
When Robin finished working at Masala in May 2013 she was owed nearly $25,000 in wages and holiday pay.
Defence lawyer Ron Mansfield admitted his clients gave in to the temptation of exploiting their workers.
"The restaurant concerned would receive frequent contact from individuals seeking offers of employment and support for visas," he said. "It is accepted the defendants succumbed to these requests and then capitalised on the individuals' desperation for that kind of support."
Mr Mansfield said it was important for the community to understand the Masala chain employed 177 staff who were paid and had full visas.
