Not in my opinion, looks plated, there seem to be rust areas on the bottom, #2 photo. That is certainly an interesting decanter, shows our ancestors had style.
Many years ago, before I had some sense, I was in an antique shop, the type that sellers rented out a booth to sell there wares. I spotted a large coffee or tea decanter, picked it up to look over, sterling along with some other marks on the bottom. I really did not know what too look for, thought to good to be true and cast it off as sterling silverplate since the price indicated such. I got home and did an online search and sure enough, that decanter was .925 solid sterling !
You guessed it, I hightailed it back to the shop, 20 miles away and it was gone. Have not found one since although have seen many plated that were tagged as solid sterling.
That was a long drive back home