Note: If you wanna discuss the restart of Gintama, please move to the thread below.
Director of Gintama Says 'We Shall Be Back'

In the episode 193 aired on TV Tokyo, Gintama anime was announced to end next April. Hinting the end of the series is a usual joke of Gintama, so there is a slight possibility that this is another one.

Sources: Screenshot of ep193, Screenshot2, Screenshot3

Updated on Jan 29th
SUNRISE staff also disclosed in the twitter post that Gintama TV series will end next March. Still, it can be a joke.

Source: eli_ossan's tweet

Updated on March 25th
The final episode was aired on March 25th. "Yorinuki Gintama (rerun of selected episode)" will start from April 5th.

Source: Screenshot of the final episode, Screenshot2