I agree with my colleague, affidavits cannot be the only evidence you have to prove that you have been physical present, but when evidence is taken into the aggragate affidavits can be very helpful, especially depending upon who provides the affidavit.
I would recommend discussing this more fully with an immigration attorney it is part of their job to find evidence that you may not think is helpful or you do not consider at all. But in light of your facts there does not appear any reason that you should not apply for DACA however an attorney will be able to advise you more specifically. Good luck.
I disagree that CIS rarely takes affidavits into account. In conjunction with other evidence, affidavits can be very helpful in bridging some gaps in time. The best advice is to retain counsel and fully discuss your history. A four paragraph post doesn't give any of us a good feel for who you are and therefore we can't identify potential evidence avenues.
Affidavits can strengthen the case but they should contain sufficient information. I do recommend you work with an attorney.
Dhenu Savla, Esq.
This answer does not create an attorney-client relationship and is not meant to be relied upon as legal advice.