I think specific knowledge is required before a good swot analysis can be done.
Unfortunately I don't have that specific knowledge.
But I can help you with the following, based on the assumptions that GAP has a ready and comprehensive infrastructure of distribution.
1) Branding - personally i feel GAP has strong branding in the everyday basics, from casual to work wear etc.
2) Infrastructure - allows for ease of distribution nationally and internationally.
3) Quality - consumer trust in quality is built
1) Formal evening wear/ party clothes : I'm not sure about internationally, but in Singapore, it is not known to be the first choice of many who are searching for party clothes. Like I mentioned, we go there for the basics.
2) Marketing : a strong brand it may be, but marketing is not as strong in Singapore.
1) Rapid changing fashion trends : any clothing store that falls behind in these will lose out a chunk of its market share.
2) Rising production costs will reduce profit margins
3) Breakdown in distribution network.
1) Using Singapore as an example, more marketing can be done.
2) New market share : the younger and hip crowd - following up on the point on expanding their range of clothes beyond just the basics.
3) New products : expanding beyond clothing to include more shoes, handbags etc... not sure if GAP already carries these.. or if the branding on such items are strong.
More homework needs to be done, specific to GAP. A swot analysis on GAP is different from just doing a swot on clothing shops in general. Go ahead.. think it through.
However, do note that in any business, it is important to have a target market. Trying to expand beyond means or targetting everyone and anyone will result in dilution of customers' interest. Like I mention, I don't quite see young adults heading to GAP for party clothes. But this may not be GAP's main target anyway.
P.S : GAP's storefront in Singapore, not too outwardly trendy.. not sure bout those overseas.