You can bet the following amounts per round:
250,000 coins T
250,000 coins CT
50,000 coins Dice
There's also a total round limit of 1,000,000 coins bet across all sides, however, bets on T and CT counteract each other.
Examples
If you bet 1,000 coins on T and another player bet 1,000 coins on CT, the difference to the overall limit is 0
If you bet 1,000 coins on T and another player bet 2,000 coins on CT, the difference to the overall limit is -1,000 (999,000)