The question gets asked a lot on Chinese forums as well- a short answer: There's zero record of his activities from Chinese sources, but many of his stories can be corroborated directly and indirectly. Others are outright fabrications, with important customs/cultural ideas ommitted, and his own role is likely heavily exagerrated if not outright fabricated in many instances.
He claims to have the personal patronage of Kublai Khan (忽必烈), having been made governor of the large city of Yangzhou. There is zero record of this, and while there were certainly large numbers of foreigners in the city, a 23 year old Italian would have been worthy of comment and it is reasonable to expect some record, where there is none- it would have been incredibly rare and unlikely, even for a Dynasty like the Yuan that made extensive use of foreigners. While it is not impossible he visited, it is safe to say that it is highly unlikely he held the post he claimed.
He claims to have helped taught the Mongolians to make use of cannons in the siege of Xiangyang. The use of cannons to assault the city is recorded, but it was a Persian, and occurred in 1273. Marco Polo did not even arrive in China until 1275 by his own account. In this case, it is completely impossible for him to have witnessed or participated in the siege, and was simply related a true event, expanding his role. Again, this doesn't mean he didn't visit, but it does prove he is not above exagerrated his own role. It does mean he certainly had contact with people who did live and have extensive knowledge of the country.
He utterly fails to mention tea, Chinese characters and writing, and other customs that most Western commentors visiting on China would have certainly mentioned. We can infer if he did visit, he likely had extremely limited contact with local Chinese, especially any Chinese merchants or elite. This is possible; he spoke no Chinese, and may have been nearly completed isolated in a bubble of Persian, Mongolian, and Turkic speaking Yuan officials. Again, he could remain in this bubble for 18 years while doing much of what he claimed- it isn't impossible, but it is unlikely. After all, he never learned Chinese at all- so maybe he simply didn't want to talk about the language or characters as a result. And hated tea, so never even wanted to discuss the custom.
He often uses Persian and Mongolian names for places. This supports the idea that if he did spend time in China (or an extended period), it would have been with Persians and Mongolians, without much contact with the Chinese.
He has very limited knowledge of Southern China, with many mistakes in descriptions. It is unlikely he visited, and was likely relating secondhand information. However, his memory may not have been perfect, and as a foreigner who didn't speak Chinese, the myriad mistakes throughout the book are common for people recalling places and events from years past.
Many specific events, such as the names of three messengers sent by Kublai Khan in 1291, are corroborated perfectly.
There are precise and accurate decriptions of historical sites and buildings that he would have to have either seen in person, or seen pictures, or heard directly from someone who had visited.
Overall, we can draw a few conclusions:
Marco Polo likely exagerrated his role and importance in several instances.
If he did not visit, he had extensive contact with Persian, Arab, Turkic, Mongolians, and others who did spend time there and who had firsthand knowledge.
After that, it gets to more of a guessing game. We cannot meaningfully say "He definitely visited and it's mostly true, other than a few lies like being at Xiangyang" or "He never set foot in China, he just spent a lot of time in Persia and Central Asia, talking with the merchants and officials there, and related what they had seen firsthand".
The truth may be in the middle- he visited, but only stayed briefly in areas firmly under Mongol control, in the company of Persians and Mongols. This would explain his lack of familiarity with Chinese culture and language, and very formulaic (and often wrong) descriptions of Southern China, as there were fewer Persians, Turks, and Mongolians the farther south you went. Some interpret this as him as never having visited and only having secondhand information, which would have been much less complete for Southern China, but whether or not he was personally there, it reflects a weaker knowledge among his Persian and Mongol sources.
TL;DR There is zero direct record or mention of his name in Chinese sources (or other primary sources of the time) There is only indirect evidence, in the form of events and people he described accurately. This could be secondhand knowledge related to him, but it is impossible to say. It is certain he fabricated his role and presence at Xiangyang, and likely he did so in other places as well (such as being an official at Yangzhou).
Whether or not he spend 18 years there, he information is almost entirely related through Mongol, Persian, and other foreign sources. However, this could have been him being isolated from Chinese society while still being physically present, or it could have been him being outside the country (or only in certain parts), relating secondary information brought to him by merchants.