I think
nessuno ha più fiducia in lui
can be translated as
nobody trusts him anymore
but also as
there is nobody that trusts him more (... than she does)
Is that correct? How can I distinguish between them?
I think
nessuno ha più fiducia in lui
can be translated as
nobody trusts him anymore
but also as
there is nobody that trusts him more (... than she does)
Is that correct? How can I distinguish between them?
Both translations are correct. Although a more natural version of the second translation might be
No one trusts him more [than her]
As usual in these matters, the correct translation depends from context. Think about the English sentence I missed him, which can be translated in Italian as L'ho mancato [con un sasso] and Mi è mancato. How do you distinguish the two meanings in English?
The OP asks if I can give a small addendum that clarifies the meaning. I cannot think of something 100% foolproof but you can certainly nudge the interpretation one way or the other. For example
Ormai nessuno ha più fiducia in lui.
Suggests the translation No one trusts him anymore, since ormai implies a different status from the past. On the other hand
Nessuno ha più fiducia in lui di così
Means, literally, No one trusts him more than so, thus making it clear that it is a comparison.
It seems to me,
Nessuno ha più fiducia in lui di lei
might be translated as: no one trusts him more than they trust her, whereas
Nessuno ha più fiduci in lui che lei
would imply that no one trusts him more than she trusts him.
But it is a bit awkward.