In the film Gravity, Stone makes her way to the Chinese space station. When they reached ISS, we saw that the crew of the ISS had abandoned the station, taking one of its two Soyuz capsules. There was no similar explanation for where the crew of the Chinese space station were. Is this station not always occupied?
Whilst accurate in many details, Gravity is not accurate in others, most notably in the relative orbital arrangements of Hubble & the International Space Station (ISS). Details about the Chinese Tiangong space station don't appear to be accurate either.
The US Space Shuttle had its last flight in July 2011, the Tiangong-1 space station was placed in its final orbit in October 2011, so in our history they have never been in orbit together. In addition the Tiangong-1 space station is much much smaller than the Chinese station shown in the movie. There are plans for larger Chinese stations, but the plans shown in Wikipedia indicate that they all have single docks for Shenzhou craft. If this were the case, then if a craft is docked then there must have been crew on the space station. It would appear that even though the future Tiangong-2 & -3 are designed for continuous operation, they don't have a continually available 'life raft' craft. In this case, if the crew had abandoned the station - they would have taken the only craft available.
I think we are meant to presume, given that it appears to be a large station - that it had multiple Shenzhou craft docked, and that Stone was able to take the life raft. The crew of the station are assumed, like the ISS, to have taken the primary vehicle and returned to the surface as soon as the scale of the accident is clear.