I searched for the current means test guidelines for SWA, but since the Department moved to the gov.ie portal, a lot of the detailed information seems to have been lost. I'm going from memory here, so apologies if any of these guidelines have changed.
As a guide, if your assessable income is greater than the maximum SWA rate for your family size, your wife won't qualify. The 2020 rates are €201 for a single adult, €134.70 for a qualified adult (aka adult dependant) and €36 for each child under 12 / €40 for each child over 12.
For example, if there are only 2 of you, and your assessable income exceeds €335.70 pw, there is no entitlement.
Assessable income will include your wages (gross less PRSI, Superannuation and Union Dues but not tax), savings (the first €5000 of savings is disregarded) and any property you might have other than your own home.
For Jobseeker's Allowance, your income is assessed as per the information on this page:
Explains how your income from work and your spouse's income from work can affect your rate of Jobseeker's Allowance.
www.citizensinformation.ie
I can't recall if the same calculation is used for SWA.
Savings are assessed as per the information in the link that Feemar5 posted above.
You could contact Citizens Information by phone (there's a link to request a callback on the page above), they should be able to give you more details and you can decide whether to proceed with the application.