For a tilemap the best way is to use a sf::VertexArray (there are a few examples floating around in the forum).
If you want to draw multiple entities of the same texture, it only depends on your game engine design, what fits your needs most.
In all cases you'll have to make sure that you don't load the same textures twice but share them under your sprites.
The reason it's okay to have many sprites is that the sf::Sprite class is light weightened thus it doesn't matter so much (if we don't talk about tens of thousands).
If you got a more specific example we might have a more specific answer.