How Long Would I Need Braces for Teeth Gaps?

Generally speaking, a matter of months is likely all you would need (based on the photo). Invisalign will usually move about 0.2 mm per aligner, each one worn for 2 weeks.
Seek a consultation with an orthodontist or Invisalign provider dentist and see if you qualify for Invisalign Express (treatment lasting less than 5 months).

I don't have a lot to add to what has already been said other than PLEASE make sure that your airway is evaluated BEFORE any orthodontics are performed. PLEASE DO NOT just arbitrarily retract teeth to close gaps, this type of treatment could lead to disastrous results for your overall health. It also appears that you have a posterior crossbite which would prohibit you from using Invisalign (at least initially) to treat your case.Good luck!

I highly recommend you see an orthodontist for a consultation.  When spaces between teeth are closed, sometimes torque is lost which means the teeth are leaned back giving them a dished-in look.  Also, your overbite will deepen.  It's often more complicated to have the best possible result than it may appear at first. I have not seen enough information to give a complete diagnosis and treatment plan but I think it is likely your treatment will take about a year.

Thank you Gabriella for your question. It should take less then  year, and more likely something close to 6 months , to close gaps gaps between the teeth, assuming there are no other problems.

Your mild upper and lower spaces could be closed within 4 months with Invisalign.

The teeth could be pulled backwards and inwards or closer to each other in order to close the gaps.

Dr R Kumar BDSLDSRCS