Sources added that Pochettino, who spent five years with Spurs before his sacking last November, has been in negotiations with PSG for two weeks.
The Argentine boss spent two years of his playing career at PSG, where he won the UEFA Intertoto Cup in 2001.
Sources have told ESPN that a number of players expected Tuchel to get the sack, but he was liked in the dressing room.
Sources also said Tuchel held meetings with club president Nasser Al-Khelaifi and sporting director Leonardo, and it was decided to replace him last week due to his tension with Leonardo and a lack of playing style.
The French champions suffered a 1-0 home defeat at the hands of table-topping Lyon on Dec. 13 before a goalless draw at Lille on Sunday.
The departure comes four months after Tuchel led the club to their first Champions League final, where they lost to Bayern Munich in Lisbon.
Tuchel was appointed on a two-year contract in 2018, replacing Unai Emery, and won the Ligue 1 title in his first campaign before claiming a domestic Treble in his second as well as reaching the Champions League final.
However, his third season in Paris was overshadowed by a disagreement with Leonardo over player recruitment.
In October, Tuchel publicly criticised Leonardo and said: "We lose too many players on free transfers. It is too, too much. We cannot ask this squad the same thing as we did last season."
Leonardo responded the following day, after PSG's 6-1 win against Angers in Ligue 1: "I didn't like his comments. The club didn't like them either.
"We have to understand the moment we are going through. If someone is not happy, it is easy -- we can talk. But if you decide to stay, you have to respect the people above you."
Thiago Silva, Eric Maxim Choupo-Moting, Thomas Meunier, Edinson Cavani, Tanguy Kouassi and Adil Aouchiche all left PSG over the summer, although they did sign Alessandro Florenzi, Moise Kean and Danilo Pereira on loan and Rafinha on a free transfer.
Tuchel parted ways with Borussia Dortmund in May 2017 amid reported disagreements with the club hierarchy, despite guiding the club to the DFB Pokal title three days earlier.
PSG return to action when they face a trip to Saint-Etienne on Jan. 6.