A "요즘은 어떻게 잘 지내세요?" B "네, 덕분에 (잘 지내고 있습니다)." yes, thanks to your kindness 덕분 means a favor, kindness, help or consideration Literally,덕분에 means "by your favor" or "through your favor". But, sometimes, 덕분에 means or "responsibility (for)" ironically in a sarcastic manner or situation. 망했다! 이게 다 네 덕분이다! Damn! That's all your responsibility!

~덕분에 = thanks to.. In short form I think it means "yes, thanks to you [I've been doing well]"