Yes, NAFTA benefits the companies of its member countries, because it helps reduce costs. Lower costs means that the companies can expand to other NAFTA countries, because they can afford to take their products there, because taxes are not so high. Because different companies make different products in different companies, there are likely untapped markets in other countries, that NAFTA companies can take advantage of.
The NAFTA trade agreement disproportionately helps America and Canada and disadvantages Mexico. The number worker permits that the United States gives to Mexico is not enough. There is a high demand for workers from Mexico in the United States particularly in the meatpacking industry. Agriculture also has a great demand for workers from Mexico.