The man, in his 20s, suffered life-threatening injuries when he was hit by the train at Stockwell, south London, on Friday.
British Transport Police said that while he remained critical, his condition was now considered "stable".
Transport for London (TfL) said the station was not overcrowded.
Nick Brown, from TfL, said the accident involved a train entering the Northern Line platform of the underground station at about 09:00 BST.
He said the organisation had "established that, while the station was busy, the platform was not overcrowded".
Eyewitnesses described the incident as "horrific".
Twitter user Super D said he saw the man get hit by the train "as he bent over to get his bag".
Others said people were screaming when they heard the impact and saw others attempting to help him before paramedics arrived.
A man struck by a rush-hour Tube train when it is believed he bent down to pick up a bag is in a stable condition in hospital, police have said.