Like you said, it's a hypothetical situation and we can never be too sure about the outcome of this imaginary fight but one thing's for sure, a tiger knows how to defend itself.

A tiger, including the Sunderban's ones, are extremely territorial and often engage in fights with other tigers. Komodo Dragons are territorial too and engage in those fights too but they're barely any fighting. It rarely gets bloody. The dragon has a few physical advantage over the tiger but a tiger knows how to survive. A komodo lizard may not be able to defend itself like a tiger can, considering they are not used to having to do that a lot.

You're right about the venom part. The lizard can kill the tiger with it but the tiger would end the fight before that, and even if it is bitten, I think it'll be able to end the lizard before the venom does its work. Remember, komodo dragons bite their prey and wait hours for it to die before feasting upon it. It won't have those hours to wait while being in a fight with a tiger.