Hola The question is "would you like to have coffee?" and answer should be "yes, I would (like to have)". In Japanese, it's いただきます and in this case, it means はい、いただきたいです. (It's a humble word of 飲みたいです/ほしいです/食べたいです/etc.) Espero que te ayude.

If you want to know the answer "Would like you some coffee?" (コーヒーいかがですか？), and you want to say "yes, please", then it should be いただきます . It depends on the situation, but ごちそうさま（usually put です in this case) would be fine perhaps when you are visited your friend's house, and she/he ask you this question. (If you are asked at plane by a flight attendant or cafe by a stuff, you should say いただきます. Hope you can understand the differences here) おかげさまで is not correct answer to this question unfortunately. Hope it helps, and good luck with your Japanese practice from now on too!

２. ごちそうさま