China being able to "hold onto their Empire" is largely a matter of definition. If the "Empire" is defined as more or less the region ruled by the Qing (or even that ruled by the Ming), and "China" as the state that ruled this region, then China holding on to the empire simply follows from these definitions.

Moving away from these definitions, we can note that the Han and the Tang controlled much of Central Asia:

• Han empire showing the Western Regions: https://commons.wikimedia.org/wiki/File:Han_Expansion.png

• Tang empire showing the Western Regions: https://commons.wikimedia.org/wiki/File:China,_742.svg

With the mid-8th century An Lushan rebellion, China permanently lost control of this Western Region. This major loss of territory was partly made up by western expansion under the Qing, with the addition of Tibet and Xinjiang in the 18th century. The extent of this Qing expansion can be seen by comparing the extent of Ming China (yellow) with modern China, covering approximately the territory of Qing China (black):

• https://commons.wikimedia.org/wiki/File:Ming.jpg

Clearly, China did not manage to maintain the empire whole and intact.

After the Tang, China lost further territory, to the Manchurian Jurchen (Jin Dynasty), with the Song being pushed mostly south of the Yangtze:

• https://commons.wikimedia.org/wiki/File:China_-_Southern_Song_Dynasty-en.svg

China under the Southern Song invites comparison with the Eastern Roman Empire, centered on Byzantium. This loss of much of their empire was followed by the loss of the rest of their empire to the Mongols. After the Mongol conquest of Southern Song, the Chinese empire was entirely under foreign rule. It is true that the Mongols presented themselves as a Chinese Dynasty (the Yuan Dynasty), as had the Jurchen (Jin Dynasty), and the preceding Khitan rulers of northern China (Liao Dynasty). Chinese imperial continuity is only maintained by accepting these foreign rulers as "Chinese". This continues with the Qing Dynasty, also foreign conquerors - from 1644 onwards, the Chinese empire was no longer under Chinese rule, but under foreign rule. However, by conventional definition, we accept the Qing as a Chinese dynasty, and also by conventional definition, reject the Ottomans as a Roman dynasty, despite Mehmet the Conqueror's claim of the title of Qayser-i Rûm after the conquest of Constantinople. (We also conventionally reject the Carolingian Empire as "Roman", despite the title Imperator Romanorum.)

The key to Chinese "survival" was the willingness of both foreign and domestic dynasties that rose to control China being willing to present themselves as "Chinese" dynasties, and doing so in a way that was/is accepted as sufficiently "Chinese". The post-Roman "Roman" emperors in the west and the east (Carolingian emperors and later emperors of the Holy Roman Empire, and the Ottomans) are not widely accepted as "Roman", and even the Byzantine empire is often not considered very "Roman" from a western perspective (thus, the "Fall of Rome" as the fall of the city of Rome, not the fall of Constantinople). The key to controlling China was to make use of the Chinese system to rule China, with the help of the Chinese elites. The Yuan did this incompletely and poorly, which surely accounts in part for their fall from power. This doesn't mean that foreign rulers needed to become "Chinese" - the Qing made more thorough use of Chinese systems to rule than the Yuan, but also worked to maintain a distinct Manchu identity (and to the end of their rule, attracted anti-foreign rhetoric against them).