I wouldn't doubt that it's more than 140,000. I recall a few years ago when they announced the actual population (currently at around 120,000) people scoffed because they "knew" there were more people than that in the city.
Which is true, as it was estimated there were over 500,000 people here at the time. However, upwards of 380,000 of those people were from all over Thailand (mainly Isaan) and "temporary" residents. People who were still officially registered in their home Amphurs as well as migrant workers (mainly from Cambodia).
That is why the quoted population of Pattaya seems so low compared to the actual numbers. There's only about 120,000 people actually registered as residents of Pattaya.
Everyone else is either a migrant worker from Isaan (or Cambodia), a tourist or an expat.
And of course, hordes of people that used to work in the restaurants, bars, hotels, massage parlours and other places all went back to their home villages when things shut down. Still a lot of construction going on, and a lot of other businesses still running, so a lot of those "migrants" are still here.
I don't know if they can even give an accurate figure though, owing to 3/4s of the population being "migrant".