Is there a limitation in the upvote or downvote for a particular question or answer can receive?
If you look at the database schema in the Stack Exchange Data Explorer, it appears that post score is saved as an integer, which in MS SQL can go up to 2,147,483,647.
So, theoretically, the maximum score is about 2 billion. However, the maximum number of votes could be infinite, since you could have downvotes offsetting the upvotes.
With a rep gain of 10 points per upvote though, you're going to be limited by the user's reputation (also an int), so a single user could only get 2 million upvotes total, unless you account for the rep cap, which throws everything off.
In reality, the internal structure is probably somewhat different from what's shown in the public database, and I doubt we'll be seeing anyone with 2 million rep anytime soon. The highest voted question on SO is only around 4500 points right now, so I think we're probably safe.
You may count limit as following ,
Maximum Upvotes limit = total number of users - users less than 15 reputation + an unknown no of deleted users who's votes were kept after deletion + the zombie votes from migrated questions Maximum Downvotes limit = total number of users - users less than 125 reputation + an unknown no of deleted users who's votes were kept after deletion + the zombie votes from migrated questions