How many carrages has the eurostar have?

If your're talking about the TGV-TMST, incorrectly known as the "Eurostar" (but the name sounds a lot cooler!), this will give you the figures per company:

SNCB (Belgium) : 4

SNCF (France) : 16

EUKL (England) : 11 + 7 trainset North of London

that sums up to 38 trainsets, but not all of them are used as "Eurostar" anymore. The British Railways use 7 of them as internal commuters, and the French have 3 trainsets they use as regular "TGV".

So one can say only 28 of them are Eurostar.