Reuben, Simeon, Levi, Judah, Issachar, Zebulun, Benjamin, Dan, Naphtali, Gad , and Asher, and those who were already there.  Joseph and his family were fruitful, increased abundantly, multiplied, and grew exceedingly mighty.

So, as he describes the growth of the nation of Israel in Egypt, he uses the terms fruitful, increased abundantly, multiplied, who grew exceedingly mighty.  The seventy who went to Egypt had indeed multiplied to 600,000 men above the age of 20, which means a possible population of as many as 3,000,000 people.  So, indeed, they were fruitful, increased abundantly, multiplied as they were in Egypt.

Now the LORD had prophesied to Abraham that his descendants would go down to Egypt and God would make of them a great nation there, but He would bring them up out of Egypt in 400 years.  So, the 400 years of that sojourn in Egypt are about over.  When Jacob prayed at  Beersheba, God said, “Go down to Egypt,” or, “Do not be afraid to go down to Egypt; I will make of thee there a great nation.”  And so, God has kept His word; the prophesies that He made to Abraham and Jacob have now been fulfilled, a great nation has formed during this period in Egypt.