If using a flexitask, can you have a flexitask require a certain number of approvals instead of a Majority only. For example, I have a committee that needs to vote on an item. They require 5 of 7 approvals before the item is approved. Can this be done?
Well you can use two options in "Assignee Options" in your flexitask configuration. You can either choose Majority must choose a specific outcome option, so that once more people approves, than disapproves and Nintex engine is aware of that, the task will be approved. You can use as well: Majority decides option, so that it will be set to the most popular outcome.
I'm surprised in on-premise there is no such options as you have in O365, so that you can set a percent of approvers, who has to decide.
If you want to have a very precise control over the number of approvals, I see no other option than to put approvers in a dictionary and then make a foreach loop to assign a task to each approver. On each "approval" increment "approvals counter" with 1, then once you reach 5 you can break the loop and set item to be approved.
If you store the taskID's for the flexi task, after all responses are received you could then query for those tasks, evaluate the responses, then have logic in your workflow to do whatever you want based on how many approval responses you received.