Hisense is definitely going to provide Android updates with 4.3 coming this fall. I read that from a Hisense customer support person commenting on an Android developer board. Another on-line comment was that although Android 5 is supposed to be released this fall, devices other than those made by Google will typically get it no earlier than the 2nd quarter of 2014, so 4.3 this fall isn't really lagging far behind the sort of updates you'd get from most hardware manufacturers. If Hisense provides 4.3, they'll probably provide 5.0, too, by Q2 2014 but there are no guarantees of that from any hardware manufacturer other than Google.
Note that Hisense has already provided an Android kernel update and three new drivers in their first 52.2MB update and an important Android security fix in the more recent 1.7MB update, so be sure your tablet has downloaded both of those.