The Verdict: Unlikely
The one-year route through marriage probably does not survive your spouse's death, so do not rely on it. If you have a Brazilian child, apply on that ground instead: it gives the same one-year route.
We are sorry for your loss. The law gives the reduction to someone who has a Brazilian spouse or partner and is not separated when naturalisation is granted. It is written in the present tense, and whether a surviving spouse still qualifies is not settled.
Your residence permit does not end automatically on a death, but it can be reviewed, so establish its basis early. Without a Brazilian child, your residence counts towards ordinary naturalisation at four years.