Your question: Do Actions with Multiple To Hit Rolls with Help provided get Advantage on all Rolls?
The Help action has the following description:
Alternatively, you can aid a friendly creature in attacking a creature within 5 feet of you. You feint, distract the target, or in some other way team up to make your ally’s attack more effective. If your ally attacks the target before your next turn, the first attack roll is made with advantage.
This means, as has already been said, that a single Helper can only give advantage to the first attack roll.
However if you had a series of helpers it is possible that the DM would allow each to have a prepared action to Help using the following kind of description: "if they make an attack I then help them attack" or "if they make two attacks I then help them attack" etc.
A prepared action interrupts, so these would come into play after the attack that triggered the action but before the next attack. So the rule from the description of the Help action:
If your ally attacks the target before your next turn, the first attack roll is made with advantage.
would apply to their first attack roll after the Help action is taken. You would get as many rolls at advantage as you have helpers that have properly ordered their prepared actions to Help.
Where a DM may disallow this is if they feel an attack action cannot be interrupted "mid-attacks". However an attacker can move between attacks, so it is pretty clear that each attack is a separate thing and it would also be possible to have a prepared action based on, say, casting a Wind Wall if an enemy uses a ranged weapon as one of their multiple attacks and that would interrupt, so I don't see a problem here.