So now its not clear if cantrips are overall character level along with the invocations? This got a bit more confusing.
It is unbelievably clear, its based on Level.
For example, Firebolt: 'This spell’s damage increases by 1d10 when you reach 5th level (2d10), 11th level (3d10), and 17th level (4d10).'
Level is always what was sometimes called 'Character Level' in previous editions.
The Multiclass Spellcaster Table is an option rule only used for determining the spell slots for multiclass characters and is not used to determine any sort of 'Caster Level', as 'Caster Level' is not a concept that exists in 5e.