There isn't really anything you can do at this point, if we are talking about your 2016 tax return. If you are eligible to make a deductible contribution to IRA, that would reduce your Adjusted Gross Income and in turn your tax due. You have until April 18 to make an IRA contribution. For eligibility information see: 2016 IRA
Deduction Limits.
Gifts to individuals are not tax deductible to the person making the gift. The only gifts that are deductible are those to Charitable Organizations that have received a 501(c)(3) designation from the IRS. Such gifts are deductible as an Itemized Deduction (on Schedule A). They must be deducted in the year the gift is made.
The best way to reduce capital gains is to "harvest" capital losses. This is where you sell positions you own with losses in order to offset gains. If your gains are in 2017, you can sell positions with losses to offset them. If your gains are from 2016, there isn't anything that can be done.
