"I'm looking forward to more families benefiting greatly from this measure."
I don't see any issue with the sentence.
It means "I'm looking forward to an outcome whee more families benefit greatly from this measure."
"more families benefiting ..." is a gerund-based noun phrase describing a situation or outcome, so it can be used as a subject, object, or a complement of a sentence, or an object of a preposition as in this example.
Gerund phrases come in two kinds, with or without a subject. When it has a subject, it can be nearly as versatile as a general noun clause, as we see in this example.
Other similar gerund phrase examples:
(with no subject of its own - it defaults to the subject of the enclosing clause)
- I love swimming (a gerund used as an object of a verb)
- I love going fishing on the weekend.
(with its own subject)
- Your [or You] standing there doesn't bother me at all = Even if you stand there, it doesn't bother me at all.
- It was a time of everyone fighting everyone else = It was a time when everyone fought everyone else.