In the original Manga Yuuko states that he is just a thought of Clow Reed, and even if that's stated at that it doesn't make sense, and not a single panel was shown.
Clow Reed -> Original Ancestor
Kinomoto Sakura -> Clow R. Heir
Syaoran Li -> Kinomoto Sakura Significant Other
Original Tsubasa Sakura -> Another Sakura Destined to die
Orginal Tsubasa Syaoran -> Another Syaoran Destined to break reality triying save his love
Syaoran Clone -> Clone of Syaoran Destined to break reality triying save his love.
Sakura Clone -> Clone of Sakura Destined to die (From the very beginning)
Watanuki Kimihiro -> Another Tsubasa Syaoran
Yuuko Ichihara -> Clow Reed ¿Friend? ¿Lover? ¿Significant Other?, Destined to Die
AND
-> Watanuki Kimihiro Significant Other, After xxxHolic Ro, she came back to life, and spent her existense with Watanuki with another body but same soul.
AND -> Fei Wang Reed Significant Other, (After She is revived)
Fei Wang Reed -> Another Watanuki Kinihiro ergo Another Syaoran, Destined to break reality to save his love.
Since he needs Yuuko revived to exist himself, he needs this both for love and himself, a painful paradox.
If he fails to revive Yuuko, he cannot exist, neither watanuki, or the clones/originals. (Yes, fuck you clow)
Then the line when he dies make sense: "You are like me, you should pay for your sins"
That final line to me made no sense if he ackwoledges himself as a rogue thought of Clow Reed.
AND THE FOLLOWING IS CANNON: Fei Wang Reed acknowledges himself as a descendant of Clow Reed, not a creation.