"Do you see me?"
Translation:Seht ihr mich?
You're confusing a few things. "Sie" has to be capitalised in order to mean "you" (formal), but "ihr" is only capitalised if it means "your" (formal). If it's not capitalised, it can mean "you" (informal, plural), "their" or "her" depending on the context and position within the sentence.
Siehst du mich? = Do you see me? (informal, addressing one person)
Seht ihr mich? = Do you see me? (informal, addressing more than one person)
Sehen Sie mich? = Do you see me? (formal, addressing one or more people)
Sehen sie mich? = Do they see me?
Sieht sie mich? = Does she see me?
Das ist ihr Fahrrad = This is her/their bike