No, he didn’t. The assembly line existed before Ford applied it to cars.
[1] https://www.wiley.com/legacy/products/subject/business/forbe...
* Tesla produced ~250k vehicles (cumulative as of Q2 2017) prior to the first production Model 3, so it's not appropriate to compare them to a brand new company: They know how to build cars by the time Model 3 rolled around. This is their 4th vehicle model.
* Tesla has stated many times how the Model 3 is a far simpler and trimmed down vehicle compared to the S or X: production should be easier.
* Tesla had a goal of 2,500/wk by December 31st (they managed 793 the last week by shutting down S&X production) and a total of 2,425 for that entire quarter.
* Tesla had a goal of 5,000/wk and a revised goal of 2,500/wk by March 31st but only managed to hit 2,020 by that point, again which required shutting down the S&X lines.
* The new goalpost is 5,000/wk by June 30th.
* Elon said that "excessive automation at Tesla was a mistake" and that "Humans are underrated". [1]
If Musk himself is suggesting that the Model 3 delays would have not occurred due to human assembly instead, I think it's quite fair to compare against Ford's Model T assembly line a century ago. Not to mention a few advancements in technology since then which should give Tesla the upper hand.
For comparison on mass production: "more than 15 million Model Ts were manufactured in all, reaching a rate of 9,000 to 10,000 cars a day in 1925, or 2 million annually" [1]. Toyota was producing 13,400 units per day in 2014.
Model3 is currently somewhere around 300 to 500 per day.
[1] https://en.wikipedia.org/wiki/Ford_Model_T