No, not really.
The answer doesn't quite fit the question. Someone is asking you about your plans for tonight, so you should tell them about your plans.
'I think I'll meet' is a supposition about the future. You might say, for example, 'I think I'll meet a lot of interesting people when I go to to study in the USA next year.'. This is just what you suppose may happen - this is not a plan.
A more natural answer would be, for example 'Yes, I am. I'm meeting a big group of friends and we're going to a bar'.