"how can she get work credits? Can I give her 1099 from my business so that she gets some credits? Or will w2 give her credits "
If she actually performs material work for the business, you should have been compensating her all along. (you can file amended returns, although this will be complicated because you will not only need to report her compensation, you will need to adjust your business return to reflect the expense). Or if she will start performing material work, and you pay her a fair market wage (what you would pay an unrelated person to perform the same duties) then that's perfectly fine. If it would be sham job just to get credits, that could be viewed as benefits fraud.
She would get SS credits whether she is a W-2 employee or 1099 subcontractor. Which way to pay her really depends on the working relationship, the rules are the same for any other employee or contractor (ignore your personal relationship when figuring this one out). There can be penalties for misclassifying a person's role.
https://www.irs.gov/businesses/small-businesses-self-employed/independent-contractor-self-employed-o...
If you do not already have employees, hiring your wife will entail withholding social security and medicare tax and state and federal income taxes, filing quarterly form 941, a similar form with your state, issuing a W-2, and complying with any other state or federal laws and regulations about employees. (For example, state laws regarding minimum wage and certain benefits may apply even if she is a related person.) The wages and other expenses become business expense deductions on your business and taxable income to your wife, which should come out more or less even, except for the cost of the paperwork. If she has the duties of an independent contractor, you would issue a 1099-NEC and she would report her own schedule C business and pay self-employment tax, in addition to reporting your business.
