Genesis 46:15

These are the sons of Leah, whom she bare unto Jakob in. Padan Aram, with Dinah his daughter; all the souls of his sons and his daughter; thirty and three.

THIRTY AND THREE. But in the above enumeration you will find only thirty-two. However, the one whose name is omitted is Jochebed who was born as they entered the border city, as it is said, Jochebed, the daughter of Levi, whom [her mother] bore to Levi in Egypt. She was born in Egypt, but she was not conceived in Egypt. This is the principle of our Rabbis.
But Rabbi Abraham ibn Ezra replied, saying that “this is surprising. For if so, why did Scripture not mention the wonder that befell her, for she gave birth to Moses when she was one hundred and thirty years old? And why did it mention the case of Sarah who gave birth when she was ninety years old? This distress was not yet sufficient for us so that the poets came and composed liturgic poems for the day of Simchath Torah, wherein they state, ‘Jochebed, my mother, will be comforted after me,’ [implying that Jochebed survived her son], and thus she was two hundred and fifty years old at the death of Moses! Is the proof of the poets for this longevity of Jochebed because Ahijah the Shilonite lived a life of great duration? [If so, this is not a proof, for his longevity is but] an Agadic tradition or the opinion of a single authority.” These are the words of Rabbi Abraham ibn Ezra.
Now lest he be wise in his own eyes in contradicting the words of our Rabbis, I must answer him and say that in any case, there is in the matter of Jochebed a great wonder of the hidden miracles which constitute the foundation of the Torah. Jochebed was Levi’s actual daughter, and not merely his offspring, as it is written, Jochebed, the daughter of Levi, whom [her mother] bore to Levi, and it is furthermore written, And Amram took himself Jochebed his father’s sister for a wife. [Thus Amram, Levi’s grandson, married Jochebed, Levi’s daughter.] Now if we would say that Levi begot Jochebed in his younger years, just as he begot all his sons, this would place her birth soon after his descent into Egypt, and she would have been very old at the time of Moses’ birth, at or near the age stated by our Rabbis. And if we would say that he begot her after he resided in Egypt for many years — say, for a period of fifty-seven years — then Levi would have been one hundred years old at Jochebed’s birth, for when he went down to Egypt he was forty-three years of age. In that case, there were two great wonders! [Levi, at the time he begot Jochebed], was as old as Abraham, concerning whom …

כל נפש בניו ובנותיו, Our sages in Baba Batra 123 claim that the number includes Yocheved who was born at the border with Egypt, Yaakov not being part of the count of 33.

כל נפש בניו ובנותיו שלושים ושלוש. If we count the names mentioned we find only 32 names. This prompted the sages to say that Yocheved, daughter of Levi, was born on the way to Egypt when Levi’s wife had just arrived at the border so that on arrival the requisite number of Israelites entered Egypt. (Baba Batra 123) She could not have been enumerated at departure, not having born and named as yet. This is also why we find the word בנותיו, “his daughters, (pl.) “as an obscure reference to Yocheved [daughter and granddaughter being lumped together as “daughter.” Serach, being a daughter of Asher who was a son of Zilpah, is mentioned separately as a “sister” in verse 17. Ed.] Both Ibn Ezra and my father wrote that the number 33 is made up by the addition of Yaakov to the total [although he was not anyone’s descendant, so that it is difficult to see him as included in the words בני ישראל in verse 8. Ed.] According to the commentary of these two scholars the words ובנותיו would have to be understood as similar to “ובני דן,” and the sons of Dan, seeing that he is reported as having had only one son by the name of Chushim (verse 23)