I think attitudes mattered more than law, but some laws (e.g. advertising restrictions, and packaging requirements) may have helped change attitudes, but growing awareness of the health issues was the key.

In 1950 tobacco was cool. By 2000 it was very definitely not. In western Europe at least, sales of premium brands were falling sharply and volumes shifting to cheap brands - a lot less profitable even for the same volume. Long before UK law changed to ban indoor smoking most offices started banning smoking indoors, and pubs started doing so too (a major chain, Wetherspoons, gradually banned smoking at all its pubs).

The manufacturers tried to grow in other markets - one tobacco company investor relations person showed me some beautiful pastel coloured cigarettes in a very fancy box aimed at Eastern Europe. It did not work in the long run as attitudes changed globally.