I am a chess player with an international FIDE rating of 2120. There is no equivalent term of 'tilt' in chess. Because, equivalent of bad beats don't exist in chess. There is something called oversight, where a player makes a mistake that isn't expected of his skill level. But, that is not bad beat.
Poker is far more emotionally demanding. Now, I am not stating with conviction that poker is tougher. High level poker is somewhat mechanical, like high level chess. In chess the best players rack their brains only during 5-6 positions in a 60 move game. Similarly, in poker the best players play on an average 20-30% of their hands and rack their brains in 3-4 hands. I am not too sure, as I am a beginner in poker.
In an any case, what is your opinion?
In my opinion, chess is much harder than poker. In chess, to create a particular move you need to create several other moves from behind the scene on an anticipation that what would be your opponent's move. But if you opponent made an unexpected move then whole planning has to be changed or adjusted. The problem is while you are moving in one direction, you have to retreat and make a new planning in defense as well as aggression.
Chess is a game where a chain of planning from various directions are required. But if at certain point chain is broken by opponent's move then a new chain need to be created.
In short, you must have a plan-A and then there must be plan-B and plan-C and so on to back you up. In case plan-A fails then you can depend on other plans. It is highly a mental game. More deep you can think or more stand-by plans you can make, more successful you would be.
Poker is also a mental game. It depends mainly on probability theory. Since a deck of card only contains 52 cards so all probabilities can be calculated. A good player can explore all the possibilities and can predict up to certainty what the possible outcome would be and if necessary he can change or adjust his decisions. And that is how they win.
On the other hand, a losing player often don't take into consideration all possibilities. They think in general terms, not deep enough to apprehend that something negative or a bad beat may occur and not prepared to combat with that situation. And that is how they lose more.
I play and enjoy both the games. I love to use my brain more than my body.