No, it's not the continuation. Tsubasa is a completely different story from CCS.
But yes, Tsubasa and CCS' stories are somehow linked.
The Sakura Kinomoto (Cardcaptor) meets with older Sakura (Tsubasa) in her dreams. Sakura Kinomoto gives her staff (The star wand) to Sakura, saying that 'You know, everything will be all right'.
The staff ended up being a payment for Yuko later. But that's a whole different story.
As for the Syaoran in CCS, I don't think he made an appearance, though.
yes it is because you can see Sakura from Cardcaptors in it she is in the beginning with her Son which is Li syaoran named after his father from cardcaptors Now Li from CCS never appears in the show but in the manga he is mentioned Sakura from CCS is also show in both ova's in Tokyo when sakura (clone) goes to get the treasure she see's her and she is also seen in shunraiki after (clone) sakura get's taken when Fai is talking about how he knew sakura was a clone they are shown side by side hope this helps your question
No, Tsubasa Chronicles is not a continuation to Cardcaptor Sakura. CLAMP uses a literal device called a crossover. CLAMP uses the same characters from these two animes and shares them. The characters may be the same, but their plots are different. EX: Sakura Kinomoto from cardcaptors is a 4th grader at Tomoeda elementary. She collects clow cards. In Tsubasa Chronicles, she is the princess of clow country who loses her memories in a form of feathers.