Nicholas Heavner died in 1769. He was not present at the massacre.
But, yes. There is evidence that his widow married Christian Lauer. One of Nicholas Heavner's daughters is called "Lauer's stepdaughter" on a baptismal recording in Stouchsburg, PA, June 23, 1773.
The Lauer, Heavner, Theiss, and Seybert families had a complicated and heavily intermarried relationship:
1)Nicholas Heavner's wife, Elizabeth Seybert, was the sister of Christian Lauer's previous wife Catharine Seybert. Elizabeth, widow of Nicholas Heavner, married second Christian Lauer.
2) Both Catharine and Elizabeth (the wives of Christian Lauer) were sisters of Jacob Seybert who was killed at the massacre
3) Christian Lauer's sister, Susanna Barbara, was married to Matthias Theiss (Dice) who was the father of Matthias (Jr) and George Dice who also moved to the South Branch basin.
Christian Lauer appears to have been a key figure in the early settlement of a part of the South Branch basin. As indicated above he was closely related to three of the early settler families and he appears to have been the contact man in Tulpehocken and Stouchsburg for other early South Basin settlers including my ancestor Michael Mallo.
There is evidence of loan repayment to Christian Lauer from several South Branch basin settlers in the early probate records.
Update - I failed to mention in the original post that Elizabeth Dice, the daughter of Matthias and Susanna Barbara Lauer Dice, was married to Jacob Seybert.