「あなたたちのクリスマスを楽しんでいる姿に影響された」は、
I was affected by how you enjoyed the Christmas.
で、どうでしょうか?
クリスマスデコレーション、料理等、あらゆる面でクリスマスを楽しんでいる様子に感銘を受け、見習いたくなりました。
[フォーマル]
I was affected by your Christmas decoration, the dishes, in every aspect of how you enjoyed Christmas. I would like to follow a good example.
[カジュアル]
I really enjoyed seeing your Christmas decorations, the dishes and everything. I want to try to emulate you.