Hi Julviano,
Based on my experience, it should work well on SharePoint Online.
For more information, please refer to the following articles:
Configure InfoPath Forms Services
http://office.microsoft.com/en-001/office365-sharepoint-online-enterprise-help/configure-infopath-forms-services-HA102476115.aspx
Add formatting rules in InfoPath
http://office.microsoft.com/en-ca/office365-sharepoint-online-enterprise-help/add-formatting-rules-in-infopath-HA102145648.aspx
If the information doesn't answer your question, I suggest you post your qusetion in this forum for a better answer.
Thanks,
Keats Ge
