Let's divide the sentence first into two clauses, two independent ones.
Hindi rin gaanong iniintindi kung ano ang kanilang magiging kabuhayan
-pagka't-
may maasahan silang magulang na matutuluyan at matatakbuhan kung sakali man.
Let's resolve an error in the independent clause so that the message is clearer.
Hindi rin [nila] gaanong iniintindi kung ano ang kanilang magiging kabuhayan.
Without nila, the verb "iniintindi" does not have a subject to perform the action.
(We don't need to include this if another subject has been implied in previous sentences)
Intindi, the root word of the verb, can mean understand or worry. In this context, it means worry.
Gaanong is an adverb here, which means much.
{Hindi} [nila] (gaanong iniintindi) becomes, [they] {don't} (worry much).
But worry here is in a transitive context, meaning it requires an object. This is begging the question of "What are they worrying about?"
The answer lies in "ano ang kanilang magiging kabuhayan".
In the sentence, we have:
ano - translates to "what"
magiging - literally "going to be" or "will be" or "become"
kabuhayan - root "buhay", which means life. In this case, it becomes equivalent to "livelihood"
It becomes:
"what will be their livelihood?"
Notice that I added a question mark. That is the translation of the "ano ang kanilang magiging kabuhayan", but adding kung makes it an included question, and therefore becomes an object:
Eliminating the question mark and rephrasing because of some english rules:
"-what their livelihood will be."
As a whole we have:
"Also, they don't worry much" about "what their livelihood will be".
This is the translation of the first independent clause. "Pagka't" is a contraction of "sapagkat", which means "because". Since:
"Also, they don't worry much about what their livelihood will be because" does not express a complete idea, it becomes a dependent clause.