Yes, you may count your earnings to qualify your spouse for an IRA contribution.
Over age 70-1/2, you may no longer make a traditional IRA contribution for yourself; but you are still allowed to make a Roth contribution for yourself.
You may not count the same earnings for both of you. For example if you only had $4000 of earnings for the year, and she contributed $3000 to a traditional IRA, you could contribute no more than $1000 (4000-3000) to a Roth IRA for youself.
