Does breast reconstruction improve survival rate from BC?

It's cosmetic.

You should know too that mastectomy reduces the risk of locoregional recurrence (but does not entirely remove it thus some people have a recurrence in the scar tissue or just below skin or in the axilla) but it does not affect the risk of metastatic recurrence - ie the cancer coming back in another organ.

As moth said, reconstruction is cosmetic. For some women, it is also psychologically necessary, something that helps them move on from having cancer and requiring a mastectomy.

The concern with reconstruction used to be the opposite of what you asked, which is whether reconstruction might reduce survival rates due to additional surgical complications added on top of the physical strains from other treatments such as chemo, or by delaying the discovery of a recurrence or by increasing recurrence risk by leaving behind cancer cells in skin and nipple sparing mastectomies.

Numerous research studies have found however that there is no survival difference between those who have reconstruction after a MX and those who don't.

Decker, you are posting on behalf of your mother, right? It would be helpful if you added a signature line indicating that it's your mother who has cancer, not yourself, because sometimes answers need to be framed differently for caregivers or family members vs. for patients themselves. As I recall, your mother's tumor was quite small, and because she is HER2+, she's had neoadjuvant chemo. Has she decided that she wants to have a mastectomy rather than a lumpectomy? And if so, is she choosing to have a bilateral mastectomy or a unilateral mastectomy? What are her thoughts on reconstruction?

Edited to add: MinusTwo, we were not only thinking the same but posting at the same time.