Sunseeker: Usually we pronounce that sentence with no pause at all. If there were a pause, we would write a comma. Note that the entire clause starting in “that” (which is optional when “that” is not the subject of the clause) is subordinate to “I think”. Structurally, it’s the same as saying “I think X”: “I think so”, “I think this / that”, “I think something, etc. That’s why we don’t see any need for a pause — the subordinate clause is part of one main clause. On the other hand, if a subordinate clause (or long adverbial phrase) comes before the main clause, (then) we do pause and change intonation phrases (rising intonation to end the first clause, resetting to begin the second one). In that case, we do write a comma.

If you say "I think that you're right" with a pause after 'that', this probably indicates more certainty than a pause after 'think'. Also note that a native speaker would place very little emphasis on the word 'that'. It would have a reduced vowel, and might be barely audible ( or missed out entirely).