Radak: Bamidbar 26:29-21 implies that he was the third son of Gil'ad ben Machir ben Menasheh. This Sefer often mentions grandsons among sons. So it mentions Asri'el, Menasheh's [great] grandson, among Menasheh's sons. He was written before Menasheh's son Machir, because Machir was a Ben Pilegesh. It did not mention Gil'ad's other sons, for they are written in the Torah. Perhaps Asri'el was mentioned because he was more honored than his brothers, and his family was known. A Drashah says that it is because his name resembles the name of their father Yisrael.

Malbim: Some say that he was, so he cannot be the Asri'el mentioned in the Torah. I say that he was Menasheh's son from his Pilegesh. The Torah did not mention him, for family heads did not come from him. Later, Menasheh married his Pilegesh, and Machir was born. Asri'el is written first, for he was the Bechor.

'Rashi': It means Asher Yaldah Lo Ishto, like "Asher Yaldah Lo l'Levi ¹ ." His Pilegesh bore Machir to him.

Malbim: It repeats "Yaldah" regarding the birth of Machir, for this was after Menasheh married her ² .

Malbim #1: This was her name. Many names begin with Hei.

Malbim #2: She was from Aram.