How do I respond as if I don't "owe" her anything?

Scenario:
There is a certain manipulator in your life who used to offer to do nice things for you (like treat you to dinner) or give you gifts. It turned out that almost every single nice act of hers was followed by her asking you for a difficult favor, so that it's hard for you to say "No." Ever since you caught the pattern, you've been declining all of her invitations.

But then she gives you an early Christmas gift using a mutual friend.

You know it's impolite to not say "Thank you" but if you text her "Thank you," there is a 99 percent probability that she will say "My pleasure!" and follow it with asking you a favor. How would you respond? When someone gives you a gift and ask you for a favor, do you find it hard to say "No"?

An example of potential conversation based on years of pattern:

Me: "Thank you so much for the gift"

Her: "My pleasure! I wanted to give this to you before I go travelling this weekend. Do you think you can drive me to the airport at 5 a.m. Saturday morning?"

How about, "I'm so sorry, I have [other plans] [an appointment] that morning?

"no, I'll be sleeping in that day. I need the sleep. Maybe you could take an Uber?"
I know what you're going through here. I've had very similar people in my life.

You could also wait until Xmas day and say thanks by text

It depends who this person is to you and what kind of a relationship you want to have with them.

You could avoid their trap by not accepting the meals and certain gifts.

You could reciprocate with like/kind gifts then feel you don’t owe anything and refuse to do the favors.

You could accept the gifts, don’t reciprocate and refuse to do the favors. This option will certainly piss them off.

“I have to be at (insert work, school, doctors, trip etc) and will not be able to drive you.”
Simple.